Currently hand-made and available only from monome.org, this USB powered control surface is a completely programmable device meant to be used with music control programs such as Max/MSP, Pd, and other MIDI, OSC etc music control languages. The website features free application software to run the device, as well, which does not require the purchase of Max/MSP, so there are no hidden costs until you start to get into really programming this as an interactive device. The website seems quite active and there are already quite a few OpenSource programs for the monome available there.
Downside is it's $500, and it's not standalone, it requires a computer (though the potential exists to build a microcontroller interface). Upside is the software allows you to program the lights independently of the the keypress reader - so they're not just toggles. It is also a multi-touch controller, which allows for much more sophisticated interaction than a touchscreen. The software could for instance wait for the third press of a key, a sequence or pattern, then draw a sequence somewhere else on the board, or start a loop, or a video. People are already writing interfaces to Abelton Live and other popular music software. The possibilities are truly limitless. The video hints at some these:
