This is a little clip somewhat explaining what it can do.
The real power of the device is its open source code, which has been explosively explored by the huge community budding around it. Numerous creative individuals have been cracking the software and hardware open to discover new ways to make use of this awesomeness.
Pre-built units and kits are offered by the creator, Tehn, on the monome site, but they consistently sell out the day that a new batch is offered. Being completely open-source, the idea has been taken up by some people to offer a way to build this coveted, always-in-demand item. This is the path that I have taken for getting one of these bad boys.
The electronic control is made possible by another open-source gadget called an Arduino. It's a USB microcontroller with easy expansion and adaptation. To allow it to communicate with the buttons and lights of a monome, I bought an unpopulated adaptor board offered by Unsped at the monome community forums. Components for that were bought from digikey. And this is what they look like:
A company called Sparkfun got in on the action by offering boards, pads, and correct diodes for the buttons. Combined with an Ebay purchase of chinese orange wide-angle LEDs, these I soldered together to make my interface:
Those little boards represent 256 solders and snips. Done while watching Juno to cut the monotony.
And that's the point I'm at right now, 6 months after I found out about it, because I can't source the wood that I would like to use to make the case. Just like it was hard to source the button pads and arduinome because of their popularity and relatively low production. But that's ok, I'm a project person...middle of a million things at once.