The Name Matchmaker (available with the Expert Tools) has to be one of the coolest features on there. Just give it a few names that you like, and click "Match Names." It then gives you a fantastic list of names - some of which you may like even better than the ones you put in!
The Expert Tools do cost a little extra. It's $12.95 for one trimester, (which is a fantastic deal!), $29.95 for 9 months, or $34.95 for a full year. They are 100% worth it, though, no matter how long you decide to subscribe.