While Library Thing is a wonderful way to get book suggestions based on my current library, I cannot imagine using it without Delicious Library! (Important note: Apple computers only).
The amazing Delicious Library software allows you to scan the bar code on your books using your Mac's built in isight camera! No typing required! After scanning your entire collection, you can then export the list and even share it on the Library Thing web site. At $40, this is a no-brainer for any one with a sizeable book collection.
Unfortunately, Library Thing charges a $10 annual fee ($25 lifetime) for libraries greater than 200 books. That's why my library stops at 200 titles.
Here is my library on Library Thing.