The majority of my books at LibraryThing. My catalog is up to 607 books, which is the better part of my library. In October, my brother-in-law asked me to estimate my book collection and I guessed that it was around 800 works, but now I'm thinking that was probably a bit optimistic. Seven hundred is likely a more realistic number.
The books I have left to add are mainly those in storage, and a good number of older books that are going to be a bit more work. They're primarily books from the pre-ISBN days, publications that range from the late 1700s to the 1950s or thereabouts. I haven't started on my atlas collection at all, for instance, and I *know* I'm going to have problems finding details on my copy of Manual For Sewage Plant Operations.
I'm pleased that I've gotten as far as I have though, and I'll probably enjoy what I've gotten up there for awhile before doing a final push to add the rest.