Android: Shake2MuteCalls is a lightweight Android application that turns motion—a sharp tap or a shake—into physical kill switch for a loud ringer. It's a great failsafe for those times you forget to silence your ringer. http://tiny.cc/androidmute
Shake2Mute uses the accelerometer in your phone to sense when you're tapping or shaking the phone and mutes the ringtone of the incoming call. You can adjust the sensitivity to suit your needs—and to keep just walking around from constantly muting your ring tone. When your phone rings just shake it gently through your pants pocket or jostle your book bag and the ringing mutes.
A donation of $1.99 enables toggles which allow you to reject calls, answer calls, and mute SMS notifications all by shaking the phone. The basic version of Shake2Mute is free and works wherever Android does. Have a favorite app for enhancing your Android experience? Let's hear about it in the comments.