A friend of mine pointed out world66.com to me. They let you create a map of the states that you've visited in. Here's mine:

Bet you can't tell which side of the country I grew up in? I decided not to count states that I'd only been in for airplane connections (California, Illinois, Michigan), but I did go with every state that I drove through on the way to spring break .... Panama City 2002, good times, good times. I figure that if I had to spend 6 hours in Virgina, I better get some credit for it :-)

They also let you make a map of all the countries in the world that you've visited, but for me that would be, ummmm, the United States and Canada, so I decided that it probably wasn't worth the effort