This could make for an excellent controller or debugger for embedded systems. The Arduino, shield, and LCD could be integrated into the keyboard itself with an I/O port for connecting to your project.

But I can't help but wonder what a determined hacker could put together with an Arduino board, a weekend and a little imagination. Google Reader Pedal: hacking a USB keyboard [Boing Boing] See Also: ...

The idea early on was to leverage existing Arduino libraries to connect with a standard USB mouse, specifically, the hardware would take the form of an Arduino Mega 2560 with a USB Host Shield.