Ah LibraryThing. Many an hour have I lost just goofin' off on that site. I do like how easy it is to add widgets on Blogger! I've had LibraryThing for awhile, though when I found out there was a limit to how many books I could list, I stopped adding things on a whim, afraid I would fill it up too fast! I just my LibraryThing booklist on the blogger sidebar, that as pretty cool. Sadly, it says their widget is not compatible with livejournal! Bah-Humbug!
LibraryThing was sort of the start of this "listing stuff" crazy. Now there are an insane number of sites dedicated to you listing your stuff! An online buddy recently showed me listal.com, a site that lets you not only list books, but dvds, tv, music, and movies that you own, want to see etc. and rate them. Here's current profile. It's another one of those sites that's a great time waster and lets you make spiffy widgets for your websites.
(I also find it interesting that both LibraryThing and Listal somehow search Amazon's site for titles and images...I guess the real question is, are they hosting the images themselves or somehow hotlinking from Amazon? Wouldn't Amazon get upset if that were the case?)
I've noticed new blogging sites, like Vox, have integrated this sort of thing into their pages so you don't have to go outside to add widgets. Here is my Vox page - you can see the pre-made widgets on the side; books lists, tag clouds, etc. Like Blogger, you can go in and organize your layout as you see fit (the page starts out much busier on Vox, I had to tell it to tone it down a bit). The nice thing is, since your books and movies are part of the site, it's really easy to add them into your posts on the webpage. (I usually do this to pretty up any movie "reviews" I do).