Conor O’Neill has used cheese and grapes as input devices with a Makey Makey and hooked it up to a Pi. He's then used them to send remote control commands over Bluetooth to an RC car. Read more about it on Conor’s blog.
Alexander Belokrylov from Oracle has written a programming tutorial to read the DS1621 temperature sensor using Java. Read it here.
Hunt the TNT with Minecraft
Matt Hawkins from Raspberry Pi Spy has improved the standard 'hunt the diamond’ game. His game, called Operation Counterstrike, places blocks of TNT randomly around the map and then challenges you to find, and destroy, the explosives before a timer runs out. Instructions to install and use the game are over on Matt’s blog.