I came across this really cool site the other day called Library Thing that allows you to create an online catalog of all of the books in your personal library. You can set up an account for free to categorize up to 200 books. If you want to keep track of more than that, you can buy a subscription for $10 smackers.
The site syncs up with the Library of Congress' catalog and allows you to enter descriptions and best of all tags for each of your books to allow for easy future searches.
Here's an example of what your catalog page could actually look like.
Though I'm not looking forward to the amount of time this will take to add in all of my info, I'm excited to have a means of finally keeping track of all of my books...that sometimes seem to disappear before I even have a chance to read them.
Most of all, as someone who is fantastic at organizing other people's lives and not so hot at organizing my own, I love all of these new tools that help make gettin' things done so much easier. Internet...I love you.