Before the mouse, there was the trackball. Built for DATAR in 1952, DATAR turned out to be a complete failure. The next user interface device that used a ball was the mouse at Xeroc Parc in 1972. Trackballs are a dying breed of interface devices. But sometimes a trackball just seems more natural choice for certain applications - not so obvious for others. Would you sit on one?
DIY Instruments: Guitar, Bass, A Drum, Yokobue, Pipes, analog synth sound effects. And for those of you who don't want to build anything - you can play the spoons.
Huge "Do it with friends" Greenhouse, Medium DIY PVC Greenhouse[pdf], Small DIY PVC Greenhouse. Now make some money with that greenhouse.