When we first heard of Social Telephone (Free, $0.99 to remove ads), the TUAW consensus that we weren't sure whether the game could be played in a reasonable period of time.
It works like this: twelve players in turn see either a phrase or a drawing. They then describe the drawing, or draw the phrase. The material is then passed anonymously onto the next player.
The game handles all the team details, passing items anonymously from one player to the next. In the end, your app updates and you can view the entire twelve-part sequence.
Here's an example of a sequence I participated in.
