Discogs.com includes data on every version of every release of Bob Dylan every anywhere in the world, and is unfortunately almost as chaotic as that sounds.
The official BobDylan.com website has not only info on every album but every Dylan song with full official lyrics.
SearchingForAGem.com maintains an incredibly complete database of the obscure Dylan releases, including all international versions, singles, promos, and appearances of Dylan songs on compilations.
The blog Untold Dylan and author Patrick Roefflaer have done a very interesting series of posts on the artwork for most of the official Dylan albums. Incredible details and backgrounds on the images and photos and the stories behind them.