I have one word for you.
This site is my brain away from home... or something like that. I have a terrible time keeping track of things on my own. Pretty much, if it doesn't get written down, it doesn't get remembered. I started my shelfari account two years ago and it has been a literary lifesaver.
I can easily organize all the books I've read, all the books I'm reading, and all the books I plan to read. It automatically suggests other books I might enjoy and gives me a place to connect with other bookaholics like myself. With a mere click of my mouse I have access to critics' reviews, friends' reviews, and synopses. I can have well thought out discussions and be inspired to read something I wouldn't normally try. (Play Book Tag is awesome!)
If you've never checked out this site go now. If you have and would like to be my friend leave me your screen name in a comment so I can add you!