It's typical of me to jump on a bandwagon long after everyone else has jumped on, gone for a nice long ride, and jumped off to catch the next one. So with LibraryThing, which was launched way back in 2005 (by a former classics student, interestingly). I finally gave it a whirl and I must say it's a delightful way to waste spend time. Much more delightful than, say, dealing with the biology experiment that is my fridge.
For what it's worth, I've used it to catalogue the books I've collected (so far) for my little project of acquainting myself with the greatest and most important works of art, music, and literature produced in the last 3000 years or so. I think it goes without saying that I've only read a fraction of these books cover-to-cover. That's not the point here. The point is that these books are the beginning of a basic library of the arts and humanities, with a few little extras thrown in.
So I invite you all to snoop around my shelves. Feel free to leave a note or 'friend' me, and I'll come look at your books.