This month's featured example, Cyclops-1000: An Electronic Eye for Rotational Speed Measurement , shabaz shows you how to make a home made test tool to measure how fast things turning. Cyclops-1000 can be used for vehicle diagnostics, to check how fast the drill is spinning, and math/physics experiments to see how fast wheels or other parts are spinning. It's low-cost (<$25) and makes a good introduction to understanding the basics of electronics and learning to solder. It gives you a chance to work with a microcontroller, a development board, build a circuit, and with the PCB it can be done by someone with no prior experience with electronics & design projects. It will give you experience programming a microcontroller and modifying code. When you're done you'll have an RPM device (tachometer) for measuring the rotational speed of all sorts of machines!