I've always been interested in names and name meanings. And the blessing that is the Internet opens up so many new possibilities for research and perusal.
One very good site is Behind The Name. I like their meanings (which I think are largely accurate), and the Related Names feature, which shows nicknames, root names, and names from other languages/places that share the same meaning.
Laura Wattenburg has created some of the most highly addicting sites ever to exist. Her Name Voyager could keep me occupied for hours. And the Baby Name Blog, in which she shares her latest revelations, is equally as enticing for the reader comments following each post. Laura has also partnered with the people at Nymbler to create a name generator based on your preferences and her analysis of styles and trends.
And just today, I found the Name Nerds, who have done great work with Celtic name translations, and who are currently conducting their own Middle Name Survey. Have a go!