ActionButton is a project mainly written in C++ and JAVA, it's free.
A button library for Arduino
A button library for Arduino (supported in Arduino 1.0 and prior versions). User can attach interrupts to events (PRESSED, RELEASED, SUSTAINED, CHANGED) or poll for state changes (isPressed(), isReleased(), isSustained(). The library also handles debouncing and provides a method to tune the debounce interval. See the example (actionbutton_ex1).