Whistler is a simple game I wrote where the microphone is used to control a spaceship through a level. In order to beat a level you end up whistling a tune.
It is very much still a work in progress, bugs surely abound. Also future incarnations may allow the user to sing or hum instead of just whistling.
Update: The precompiled versions of this don't seem to work on the latest versions of Mac OS X. Additionally, the Sonia sound-processing library I used no longer appears to be maintained and does not work on the latest version of Processing. All that to say, you may have trouble getting it running.
Built with Processing