The teacher in me searches for children's books wherever I go. I love hitting up garage sales for books (and toys) and Goodwill always has popular, barely used books. I just can't imagine spending $17 for a book when I can get it for under $1 most of the time.
I recently looked around and realized I didn't even know what books I had anymore. I knew I had been collecting books I had read to kids, popular books and books that looked interesting. But I had no way of knowing what types I owned or if I was buying duplicates. Duplicates would be fine for teaching but I had no idea which ones I had. So I decided I wanted to catalog my books.
I found this site http://www.librarything.com/ and it worked really well. All I had to do was enter the title, then the site searched for the book on Amazon. I clicked on my book and then it was entered into my library. I also put tags on the books such as, winter, teeth, bears, mice. This will be useful for teaching. The first 200 books are free to add (I entered 167 books). Then you can pay a fee. My husband said it's a beta website so it might not be around forever. So I concluded for now not to pay anything.
It gave me an easy way to see what books I have. I printed it out, so if I do find another option (such as using Excel) I can easily enter the data.