Hey LMR! I haven't made a post in a while, but I have been lurking....
Anyway, this is an air cannon I created a while back and decided it would be cool to make the firing mechanism controlled by a Wii Nunchuck. It is made to shoot bouncy balls that I got off ebay. It is pretty basic, pressure builds up and is then released by a modified sprinkler valve. When the blowgun valve (the red lever thing) is pressed, the modified sprinkler valve is triggered. To make this happen when a Wii Nunchuck is tilted, I used a high torque servo (http://www.pololu.com/catalog/product/1057) and an Arduino with code from http://todbot.com/blog/. I thought it was pretty cool so I decided to post it. It can shoot very far, but in the video I only pressurized the gun to 3-4 psi because I was in my garage. Maybe I will get some video of it outside in the future.
https://www.youtube.com/watch?v=sf3oA_ZUhkc