I know it sounds like a How-To book by Abdul Alhazred, but No Starch Press is coming out with a book called Forbidden LEGO, for creating such things as a continuous-fire ping-pong ball launcher. Here’s a video of a toy gun that shoots LEGO plates:
Found via Gizmodo, where they have another video of the gun.
I for one can’t wait until small plastic pieces are banned from U.S. airplanes.