From Aaron Booth at Uppercut:
Pop Quiz Show is a multi-player trivia game inspired and styled after retro TV game shows. What's unique about it is that it's truly social -- played verbally with a group in the same physical space (using the same WiFi network), not virtually. One person hosts and the other phones turn into a buzzer. Like a board game to play around the kitchen table or at the pub.

Get it free in the App Store.