Google's willingness to let people play with their maps has brought an avalanche of cool and fun tools. One of the coolest I've seen lately is called "beenmapped.com." Beenmapped.com is basically a wiki for interesting destinations around the world using GoogleMaps.
Anyone who's played with the satellite view using GoogleMaps has likely encountered something they wanted to show someone else. Maybe you found a lake shaped like Alfred Hitchcock's profile or a possible UFO landing site in your local park. beenmapped.com gives you a place to post it, along with comments, and lets everyone else rate your location. Even if you don't use GoogleMaps, you can have a lot of fun looking at what other people have found.
From the site: "Ever since Google Maps went online with satellite pictures, all sorts of oddities are found every day. Secret installations, UFO candidates, and weird picture defects. But those were either soon forgotten or too scattered among website forums. Now those can all be found in one place: right here."