A certain lady has over a thousand books right now, with no end in sight. I finally got her to catalog them with Librarything.com. I was amazed when she only had a few dozen duplicates, some of which came from blending our collects. Librarything allows her to check her catalog before buying a book. I've used it for years with no problems.
I am not in any way, other than a user, associated with librarything.com.
To the point: Anybody have a online catalog site they use and like? (Or used and hated?)