Platform: Android, BlackBerry, iPhone, webOS
What started as a game for hipsters is going mainstream. This popular location-based app lets you discover tips about new places just by checking in to them on your smart phone (bars, cafés, parks, restaurants, etc.). The more places you frequent, the more points you earn, allowing you to unlock special badges for positions such as mayor, which recognizes the most loyal regular. And the rewards aren’t just virtual. Foursquare has set up partnerships with scores of businesses to give away everything from free coffees to hotel stays. Bonus: foursquare users can now get Zagat tips.