Vitaly Minko created a tiny One Thumb Keyboard (OTK) using a Teensy++ 2.0.

The OTK provides customizable buttons to create your own useful shortcuts.  The tiny form factor allows it to be attached to a bezel of screen for easy access.  The OTK is particularly useful for creating shortcut keys for something like photo or video editing software.

Details of the project can be found on Vitaly’s great website.

Discussion about this project can be found on the PJRC Forum.