This tiny library ensures that a button input only triggers an event once.

To install (on OSX) or in general, Git Bash worked for me on Windows 7:

1. cd to your default Arduino directory
2. Run this in the directory git clone git://github.com/d2kagw/arduino-tap-library.git Tap
3. Open (or relaunch) the Arduino IDE
4. Select Sketch > Import Library... > Tap
5. Profit.

Examples are in the examples directory.

Enjoy.