Extreme Places to Check In to on Foursquare, Tweet

There are a few locations you probably shouldn't check in to on Foursquare, and then there are the places you probably won't get to check in to in your lifetime. These locations are saved for the extreme sports enthusiasts and those who travel beyond our planet. Take a look at a few extreme places some twitterers and Foursquare addicts have sent updates from, and add the coordinates to your bucket list!