Here's an electronics project that may not offer lots of practical applications but is cool, impressive and educational: converting an Etch A Sketch into a weather monitor
Electronics hobbyist weblog Whiskey Tango Hotel used stepper motors from a dot matrix printer to control the knobs of an Etch a Sketch. A temperature sensor was wired to the system so that temperature changes are recorded on the Etch A Sketch in the form of a strip chart.
The author used three microcontrollers to drive the motors and created a mount for the Etch a Sketch using a baseball display case. The software was debugged until it correctly "sketched" the temperature every 750 milliseconds.
A full schematic and build details can be found at the source link below.