All sorts of people are using toaster ovens and skillets to reflow (melt) solder paste on PCBs, but one bottle neck is applying paste to the pads. Using a syringe takes a long time, and getting custom made stencils is fairly expensive. tymm posted a cool instructable showing how to roll your own solder paste stencils. He uses the same process for etching your own circuit boards but does it on a thin piece of copper bought from a hardware store.
Robotic Ball Controlled by Music
Motors inside the ball work against a counterweight to allow it to move without external wheels. I believe certain pitches and sequences control how it moves. It can also play music itself–a piezo actuator uses the entire outer shell as a speaker to play back manipulated portions of what it hears. From a Robotics and Art conference that was taking place near RoboCup 06.