Those wily engineers at Yelp have combined a scary amount of the things I love into one device. They've taken a keg and tap, an Arduino, an RFID reader, and an iPad and turned them into an amazing kegerator. The device not only tracks who's been drinking but also tracks information about the beer as it's poured, including the temperature and ratings of recently poured drinks (so you'll know when the keg is on a roll). They even put together a bookmarklet to monitor and track the keg remotely.
And as if all of that wasn't enough, this was all designed during the Yelp Hackathon, which takes place over a 24-hour period. During that 24 hours, the company allows the engineering team to put together whatever they want. So yes, all of this was designed and assembled on official company time. OK, now you guys are just bragging. That's just unfair!