Most vague title ever posted on robknight.net, I know. Frappr is a cool site (although not the coolest looking) that uses Google Maps technology to allow anyone to put a virtual pushpin where they live on earth. You can create themed maps for anything you can think of. Group members can add photos and comments. As Pearl Jam is the topic of the week between me and the only other reader of this site who never comments but faithfully shows up to read every day, there is a Pearl Jam map with some great photos (like the one above) from their fall tour in South America.
I’ve also created a Frappr map for my favorite band whose live shows I can never make it to, Day One Symphony.