The Baby Name Wizard's NameVoyager is very cool:
The Baby Name Wizard's NameVoyager is an interactive portrait of America's name choices. Start with a "sea" of nearly 5000 names. Type a letter, and you'll zoom in to focus on how that initial has been used over the past century. Then type a few more letters, or a name. Each stripe is a timeline of one name, its width reflecting the name's changing popularity. If a name intrigues you, click on its stripe for a closer look.
Then there are the standards:
BabyCenter.com's Baby Name Finder lets you search for names with "starts with" "ends with" and "number of sylables" fields.
Just a note: we don't tell anyone what name we've picked until after the baby is born. In fact, we are lucky if we've decided on a name by the time the baby is born. So don't ask us.