A New Report by the Water Resources Research academic journal talks about an experiment by a team that monitored water level evaporation rates by monitoring water levels. And to do this, they used a Wiimote.
According to the report, they pointed the Wiimote’s IR Leds at reflectors that were attached to a float, in a water pan. They then used the reflected light to see the rate of water evaporation. The Wiimote worked out pretty well apparently, even picking up slight changes in the water levels, and compensate for other movements due to waves or water displacement. Not too bad for a $30 Game Controller, eh?