Harry Belafonte - "The Midnight Special", RCA (USA/UK), 1962:

R-0001 Midnight Special (Huddie Ledbetter "Lead Belly") - Bob plays harmonica for Harry Belafonte on the title track of his 1962 US RCA album The Midnight Special (stereo version). The track has also appeared on many Harry Belafonte compilation albums from 1972 to 2002. The mono version of this track is listed separately as R-0001M, and occurs only in 1962 on the mono LP and a 1964 West German 7" single.

R-0486 Midnight Special (Huddie Ledbetter "Lead Belly") - a previously unreleased alternate take from the same sessions as R-0001, released on the BMG Germany compilation May Your Song Always Be Sung Again: The Songs Of Bob Dylan Vol. 2, 2001

Carolyn Hester - "Carolyn Hester", Columbia (USA)/CBS (UK), 1962:

R-0002 I'll Fly Away (Albert E. Brumley) - Bob plays harmonica for Carolyn Hester on her first Columbia album, 1962
R-0003 Come Back, Baby (traditional) - Bob plays harmonica
R-0004 Swing And Turn Jubilee (traditional) - Bob plays harmonica

Mono versions are R-0002M, R-0003M and R-0004M.

As well as R-0002 - R-0004, the CD release includes

R-0222 I'll Fly Away (Albert E. Brumley) - Bob plays harmonica, alternate take, previously unreleased
R-0223 Come Back, Baby (traditional) - Bob plays harmonica, alternate take, previously unreleased

Victoria Spivey, Roosevelt Sykes, Big Joe Williams & Lonnie Johnson - "Three Kings And The Queen", - Spivey Records (USA), 1964 (recorded 1962):

R-0005 Sitting On Top Of The World (Walter Jacobs/Lonnie Chatman) - Bob supplies harmonica and backup vocals for Big Joe Williams
R-0006 Wichita (Big Joe Williams) - Bob plays harmonica for Big Joe Williams

Big Joe Williams, Memphis Slim, Roosevelt Sykes, Lonnie Johnson & Victoria Spivey - "Kings And The Queen Vol. 2", Spivey Records (USA), 1972 (recorded 1962):

R-0086 Big Joe, Dylan & Victoria (Big Joe Williams) - Bob plays harmonica for Big Joe Williams
R-0087 It's Dangerous (Victoria Spivey) - Bob plays harmonica for Victoria Spivey

The Broadside Singers - "Broadside Ballads Vol. 3: The Broadside Singers", Folkways (USA), 1964:

R-0458 Paths Of Victory - Bob is rumoured to sing backup vocals on this cover version by The Broadside Singers from the 1964 Folkways album Broadside Ballads Vol. 3: The Broadside Singers, now also available on The Best Of Broadside 1962-1988, Smithsonian Folkways Records, 2000

Richard Fariña and Eric von Schmidt - "Dick Fariña & Eric von Schmidt" - Folklore (UK), 1964, CD release Solano Records (USA), 2007:

R-0011 Glory, Glory (traditional) - Bob supplies harmonica and back-up vocals to Richard Fariña and Eric von Schmidt
R-0012 You Can Always Tell (Furry Lewis) - Bob supplies harmonica and back-up vocals (Bob's involvement is disputed)
R-0013 Xmas Island (Richard Fariña) - Bob supplies harmonica and back-up vocals
R-0014 Cocaine [Cocaine Blues] (traditional) - Bob supplies harmonica and back-up vocals
R-0015 London Waltz (Richard Fariña) - Bob supplies harmonica and back-up vocals (Bob's involvement is disputed)
R-0016 Overseas Stomp (Jab Jones-Will Shade) - Bob supplies harmonica and back-up vocals (Bob's involvement is disputed)

R-0019 Will The Circle Be Unbroken (traditional) - Bob appears on Ramblin' Jack Elliott's Vanguard album Jack Elliott as "Tedham Porterhouse" playing harmonica, 1964

R-0038 Downtown Blues (Frank Stokes) - Bob plays piano for Geoff Muldaur as "Bob Landy" on the Elektra album The Blues Project, 1964

Tom Rush - "Take A Little Walk With Me" - Elektra (USA), 1966:
Bob was rumoured to be the "Roosevelt Gook" playing piano, although it now seems most likely it was Al Kooper getting a second musician's fee!

R-0056 You Can't Tell A Book By Its Cover (Willie Dixon)
R-0057 Who Do You Love? (Elias McDaniels - "Bo Diddley")
R-0058 Love's Made A Fool Of You (Buddy Holly- Wes Montgomery)
R-0059 Too Much Monkey Business (Chuck Berry)
R-0060 Money Honey (Jesse Stone)
R-0061 On The Road Again (Tom Rush - not a cover of the Dylan song)

Various Artists - "Disconnected - The Dial-A-Poem Poets Double", Giorno Poetry Systems (USA), 1974:

R-0158 Jimmy Berman Rag (Allen Ginsberg/Bob Dylan) - Bob contributes vocals and plays guitar, piano and organ, recorded New York, Nov 1971, first released on Disconnected - The Dial-A-Poem Poets Double, Giorno Poetry Systems (USA), 1974, also on the 1982 Allen Ginsberg US album First Blues, John Hammond Records (see below)

R-0225 September On Jessore Road (Allen Ginsberg/Bob Dylan) - recorded Nov 1971, Bob plays piano, organ, acoustic and electric guitars on this track, a 1:17 excerpt of which originally appeared on a flexi disc given away with "Sing Out!" magazine in 1972

R-0157 Going To San Diego (Allen Ginsberg) - Bob contributes vocals and plays guitar, piano and organ, recorded New York, Nov 1971
R-0159 Vomit Express (Allen Ginsberg-Bob Dylan) - Bob contributes vocals and plays guitar, piano and organ, recorded New York, Nov 1971, also on Allen Ginsberg's 1994 CD boxed set Holy Soul Jelly Roll: Poems And Songs 1949-1993 (see below)

This album also contained Jimmy Berman Rag (R-0158).

Allen Ginsberg - "Holy Soul Jelly Roll: Poems And Songs 1949-1993" - Rhino Word Beat (USA), 1994:

R-0224 A Dream (William Blake/Allen Ginsberg) - recorded Nov 1971, Bob plays guitar and contributes vocals to this poem by William Blake set to music
R-0235 September On Jessore Road (Allen Ginsberg-Bob Dylan) - recorded Nov 1971, Bob plays piano, organ, acoustic and electric guitars on 10:34 take (for 1:17 excerpt R-0225, see above)
R-0226 Airplane Blues (Allen Ginsberg) - recorded Jan 1982, Bob plays bass for Allen Ginsberg (the 2016 booklet notes to The Last Word On "First Blues" say that this take is without Bob, even though the 1994 booklet notes say he plays here)

There are two versions of Nurse's Song (William Blake/Allen Ginsberg) on CD3 - Nurse's Song (Experience) (track 9, 2:07) and Nurse's Song (Innocence) (track 21, 7:12). Nurse's Song was one of the songs recorded at the sessions in Nov 1971, but neither of these versions include Bob.

David Bromberg - "David Bromberg", Columbia (USA)/CBS (UK), 1972:

R-0073 Sammy's Song (David Bromberg) - Bob plays harmonica on David Bromberg's self-titled Columbia album, 1972

Doug Sahm - "Doug Sahm & Band" - Atlantic (USA), 1972:

R-0090 (Is Anybody Going To) San Antone? (Dave Kirby/Glen Martin) - Bob provides backup vocals for Doug Sahm
R-0637 It's Gonna Be Easy (Atwood Allen) - Bob plays organ for Doug Sahm
R-0638 Poison Love (Elmer Laird) - Bob plays guitar for Doug Sahm
R-0088 Wallflower - Bob shares lead vocal and plays guitar for Doug Sahm on this cover of his own composition
R-0214 Dealer's Blues (Doug Sahm) - Bob plays organ for Doug Sahm
R-0092 Faded Love (Hopwood Ascheberg/J R Wills) - Bob plays organ for Doug Sahm
R-0089 Blues Stay Away From Me (Alton & Rabon Delmore-Wayne Raney-Henry Glover) - Bob plays guitar and provides vocals for Doug Sahm
R-0091 Me And Paul (Willie Nelson) - Bob plays harmonica and organ for Doug Sahm

The Sir Douglas Band - "Texas Tornado" - Atlantic (USA), 1973 (recorded 1972):

R-0105 Tennessee Blues (Bobby Charles) - Bob plays harmonica (uncredited) for Doug Sahm, recorded Oct 1972 at Doug Sahm & Band sessions
R-0151 Ain't That Loving You (D. Malone) - Bob is reputed to play on this track, recorded Oct 1972 at Doug Sahm & Band sessions
R-0152 I'll Be There (Dave Burgess) - Bob plays guitar on this track, recorded Oct 1972 at Doug Sahm & Band sessions

Doug Sahm - "The Genuine Texas Groover" - Rhino Handmade (USA), 2003:

R-0639 On The Banks Of The Old Pontrachain (Hank Williams/Ramona Vincent) - Bob plays guitar for Doug Sahm, recorded Oct 1972 at Doug Sahm & Band sessions
R-0640 Hey, Good Lookin' (Hank Williams) - Bob plays guitar for Doug Sahm, recorded Oct 1972 at Doug Sahm & Band sessions
R-0641 Please Mr. Sandman (Huey P. Meaux) - Bob plays guitar for Doug Sahm, recorded Oct 1972 at Doug Sahm & Band sessions
R-0642 Columbus Stockade (Woody Guthrie) - Bob plays piano and organ for Doug Sahm, recorded Oct 1972 at Doug Sahm & Band sessions
R-0643 The Blues Walked On In (Joey Longoria) - Bob plays piano and organ for Doug Sahm, recorded Oct 1972 at Doug Sahm & Band sessions

R-0093 Somebody's Else's Troubles (Steve Goodman) - Bob plays piano and provides harmony vocals for Steve Goodman on the title track of his Buddah album, 1973

Steve Goodman - "The Essential Steve Goodman", Buddah (USA), 1976:

R-0111 Election Year Rag (Steve Goodman) - an out-take from the 1973 Somebody Else's Troubles album released as a single, Bob plays piano and provides harmony vocals for Steve Goodman

R-0281 Miss O'Dell (George Harrison) - Bob is rumoured to be the harmonica player on this B-side of George Harrison's 1973 Apple single Give Me Love (Give Me Peace On Earth)

Booker T. and Priscilla Jones - Chronicles, A|&M (USA), 1973:

R-0094 The Crippled Crow (Donna Weiss) - Bob plays harmonica for Booker T. and Priscilla Jones on their A&M album Chronicles, 1973

R-0095 I'm So Restless (Roger McGuinn) - Bob plays harmonica and gets a name check in the lyrics on this song from Roger McGuinn, Columbia, 1973

Barry Goldberg - "Barry Goldberg" - Atco (USA), 1974:

R-0106 Stormy Weather Cowboy (Barry Goldberg) - Bob contributes back-up vocals for Barry Goldberg
R-0107 It's Not The Spotlight (Gerry Goffin/Barry Goldberg)- Bob plays percussion and contributes back-up vocals for Barry Goldberg
R-0108 Silver Moon (Barry Goldberg/[Robert?] Hunter) - Bob contributes back-up vocals for Barry Goldberg
R-0109 Minstrel Show (Barry Goldberg) - Bob contributes back-up vocals for Barry Goldberg
R-0110 Big City Woman (Barry Goldberg) - Bob contributes back-up vocals for Barry Goldberg

Thanks also to Eddie Korvin for this previously unreleased performance:

R-1654 Hi-Heel Sneakers (Tommy Tucker) - performance by Barry Goldberg with Bob on piano, recorded at Blue Rock Studio, New York, summer 1971, first published on YouTube, Dec 2016

R-0121 Who Love (If Not You Love) (David Blue) - Bob plays harmonica on this track from David Blue's Asylum album, Com'n Back For More, 1975

R-0135 Don't Go Home With Your Hard-On (Leonard Cohen) - Bob contributes backup vocals to the chorus on this track from the Leonard Cohen album Death Of A Ladies' Man, Warner Bros/Columbia, 1977

R-0153 Pledge My Head To Heaven (Keith Green) - Bob plays harmonica for Keith Green on this track from his gospel album So You Wanna Go Back To Egypt, Pretty Good Records, 1980

R-0452 Rising Sun (Hufsteter/Larriva/Marsico/Quintana) - Bob plays harmonica for the Cruzados, 1983, from the album Cruzados - Unreleased Early Recordings, 2000

R-0163 Go Away Little Boy - Bob plays rhythm guitar and probably harmonica on Lone Justice's version of one of his unreleased compositions (an out-take from Empire Burlesque): this track was only originally available as a bonus track on the B-side of the European 12" version of their 1985 Geffen single Sweet Sweet Baby (I'm Falling), but was released on CD in 1999 in a remixed version (R-0274) on The World Is Not My Home: The Best Of Lone Justice, Geffen (USA) and in 2003 on The Best Of Lone Justice: The Millennium Collection, Geffen (USA).

R-0164 We Are the World (Michael Jackson/Lionel Ritchie) - Bob contributes vocals to charity single, Columbia, 1985

There was also an extended album version (R-0632)

R-0169 No Name On The Bullet (Sly Dunbar/Robbie Shakespeare) - Bob plays harmonica for Sly and Robbie on their Island album Language Barrier, 1985

R-0170 (Ain't Gonna Play) Sun City (Miami Steve Van Zandt) - Bob contributes vocals to this 7" single version (4:58), Manhattan, 1985

There were also two album versions (R-0171 and R-0518), and an extended 12" remix (R-0611).

R-0189 Street Rock (Kurtis Blow/Bill Black/Tashim) - Bob contributes "rap" vocals to this track from Kurtis Blow's album Kingdom Blow, Mercury, 1986

R-0318 Jammin' Me (Tom Petty/MikeCampbell/Bob Dylan) - Bob Dylan is rumoured to play guitar on this co-composition from Tom Petty & The Heartbreakers' MCA album Let Me Up I've Had Enough, 1986

R-0190 The Factory (Warren Zevon) - Bob plays harmonica on this track from Warren Zevon's album Sentimental Hygiene, Virgin America, 1987

U2 - "Rattle And Hum" - Island (USA/UK), 1988:

R-0199 Love Rescue Me (Bono/Bob Dylan) - Bob plays harmonica and provides backing vocals for U2
R-0200 Hawkmoon 269 (Bono) - Bob plays organ for U2

Nanci Griffith - "Other Voices, Other Rooms", Elektra (USA/UK), 1993:

R-0215 Boots Of Spanish Leather - Bob plays harmonica for Nanci Griffith on her Elektra album Other Voices, Other Rooms, 1993

Carlene Carter - "Sweet Meant To Be", Giant Records CD single (West Germany), 1993:

R-0218 Trust Yourself - Bob contributes backing vocals to Carlene Carter's cover which first appeared on a Giant Records West German CD single Sweet Meant To Be distributed with the album Little Love Letters in 1993

R-0460 Man In The Long Black Coat - Bob is rumoured to play guitar and supply vocals on this version by Emerson, Lake & Palmer from their 1994 Victory album In The Hot Seat (re-released by Polygram International, 2000)

I suspect this is a mistake, and he doesn't appear.

R-0228 Just Like A Woman - Bob plays guitar and harmonica on Stevie Nicks' cover from her album Street Angel, Modern Records, 1994

R-0248 Tragedy Of The Trade (Bob Dylan/Gerry Goffin/Barry Goldberg) - Bob provides vocals and guitar to this co-composition
R-0249 Time To End This Masquerade (Bob Dylan/Gerry Goffin) - Bob provides vocals and guitar to this co-composition

R-0452 Rising Sun (Hufsteter/Larriva/Marsico/Quintana) - Bob plays harmonica for the Cruzados (then The Plugz), 1983
A re-recorded version of this song without Bob was released on the first Cruzados album just called Cruzados (Arista ARCD 8383 (CD)/AC 8-8383 (LP), 1985).

R-0740 Home (Dave Stewart/Gary "Mudbone" Cooper/Bob Dylan) - Bob plays piano on this track from Jan 2002 previously made available on the Internet by Dave Stewart as part of a project called Electroblues Volume One.

R-0699 I Saw Her Standing There (John Lennon/Paul McCartney) - live, Bob plays guitar with the Rock Hall Jam Band supporting Mick Jagger and Bruce Springsteen
R-0700 (I Can't Get No) Satisfaction (Mick Jagger/Keith Richards) - live, Bob plays guitar with the Rock Hall Jam Band supporting Mick Jagger and Bruce Springsteen

Both performances recorded at the Rock And Roll Hall Of Fame, Grand Ballroom, Waldorf-Astoria Hotel, New York, 20 Jan 1988. Both were included on The Best Of Rock And Roll Hall Of Fame + Museum Live - Time-Life Music (USA), Nov 2011

R-0899 One Too Many Mornings - Johnny Cash with the Avett Brothers with Bob on background vocals based on the out-take from the Nashville Skyline sessions with Bob and Johnny, Columbia Studios, Nashville, TN, 18 Feb 1969, previously released in the 1969 film and video Johnny Cash: The Man = His World = His Music

R-0157 Going To San Diego (Allen Ginsberg) - Bob contributes vocals and plays guitar, piano and organ, recorded New York, Nov 1971, from First Blues (1983, see above)
R-0159 Vomit Express (Allen Ginsberg-Bob Dylan) - Bob contributes vocals and plays guitar, piano and organ, recorded New York, Nov 1971, from First Blues (1983), also on Allen Ginsberg's 1994 CD boxed set Holy Soul Jelly Roll: Poems And Songs 1949-1993 (for both see above)
R-0158 Jimmy Berman Rag (Allen Ginsberg/Bob Dylan) - Bob contributes vocals and plays guitar, piano and organ, recorded New York, Nov 1971, first released on Disconnected - The Dial-A-Poem Poets Double, Giorno Poetry Systems (USA), 1974, also on First Blues (1983, above)
R-1648 Nurse's Song (Allen Ginsberg/William Blake) - Bob contributes vocals and plays guitar, piano and organ, recorded at The Record Plant, New York, NY, Nov 1971, performance new to this compilation
R-1649 Spring (Merrily Welcome) (Allen Ginsberg) - Bob contributes vocals and plays guitar, piano and organ, recorded at The Record Plant, New York, NY, 9-17 Nov 1971, song new to this compilation
R-1650 September On Jessore Road (Allen Ginsberg-Bob Dylan) - recorded at The Record Plant, New York, NY, 9-17 Nov 1971, Bob plays piano, organ, acoustic and electric guitars, performance new to this compilation, different from the performance on Allen Ginsberg's 1994 CD boxed set Holy Soul Jelly Roll: Poems And Songs 1949-1993
R-1651 Do The Meditation Rock (Allen Ginsberg) - recorded Rundown Studios, Santa Monica, CA, 23 Feb 1982, Bob plays bass for Allen Ginsberg, performance new to this compilation

Wynton Marsalis Septet - "United We Swing: Best Of The Jazz At Lincoln Center Galas", Red Distribution (USA), 2018:

R-1913 It Takes A Lot To Laugh, It Takes A Train To Cry - recorded live with the Wynton Marsalis Septet at the Apollo Theater, New York City, New York, 7 Jun 2004 as part of Jazz at Lincoln Center's 2004 Spring Gala