I played a game called Get The Picture when I was a kid.  It has disappeared, but the concept of making funny captions for images is still popular.  This was featured on the Twilio Blog not too long ago.

The concept is simple: The host fires up the page on a big screen, then everyone sends text messages to interact with the screen.  The host decides when to display entries and vote counts.

Try the demo out, watch the screencast, and get the source.

 I'm working on a different version of this: a web app version using Node.js and Socket.io.