I have been thinking of fun things to do with the 3rd channel for a while and here are some of the things I came up with:

1) Auto flip over system. Servo that sticks a prob out the top (or if your sneeky out the antenna whole) This actually works as I got it to work on my rc18t. Was really funny if you hit the button by accident
2) Light systems (with on off capability) I have only seen a mod where you hit a switch with a servo. Anyone seen any lights that can turn on an off via a 3rd channel?
3) Snow plow. Though I have not set this up on any of my stuff (snow plowing with a revo + .21 motor would be interesting at 40 mph)

Any other idea's?