librarything.com

I own 177 books. I did not count them all, however, I did catalog them on LibraryThing.com. Why? Why not! Actually, I was just ridiculously bored and I really did need to do something about my book shelves.

You can catalog 200 books for free or buy a membership (either $10 for a year or $25 for life) to enter as many as you like. However, there is actually nothing from stopping you from making another account after your first one is full, granted you own and have the time to catalog over 200 books.

You can also post reviews of your books and find members who share the same books and tag your books. It's pretty easy to use. I used ISBNs for a lot of my books because when typing the titles the paperback editions would show up. Also, I own some Barnes & Noble editions and it is absolutely important to specify that and well LibraryThing uses Amazon.com to find books, so ISBNs were easiest to use for me since I'm picky. But if you are not particular about the edition you admit to owning, you can just type the title--you don't even have to type the entire title. I also had to use Library of Congress call numbers for a few of my old books and some books, I just had to wing it on. So, yeah, LibraryThing.com is a very good cure for boredom. It's easy to use and well, who doesn't like joining web communities? Haha.

So, if you are bored and have a lot of time on your hands and a lot of books, you may want to try out LibaryThing.com

By the by, my catalog can be found here, if you are inclined to look.