For my junior-level instrumentation class, my team and I were assigned to create a device to calculate wind speed and direction.  Using parts from around the lab, we created this:

This device used a hobby propeller attached to a DC motor, mounted as a windmill on a potentiometer.  The wind would cause the propeller to spin, creating a measurable voltage difference across the motor terminals.  The resistance across the potentiometer indicated the direction.

The device was calibrated and tested in a wind tunnel.