Come join me at Oust.me - Oust.me is a game that is layered on top of your foursquare activity. Foursquare itself has a gamification element with the point system and mayorship rewards as well as check-in badges. But this is so meh. I thought the lack of engagement around the gamification system in foursquare would eventually be their demise. I still think that's the case. But you can at least have some fun with it now while it lasts.
Oust.me is a territory conquering game that awards badges and titles based on your conquests. Unlike Foursquare, you take over entire territories and not just single locations.