Has anyone played with the Mimo
Mimo 720S Touchscreen
http://www.mimomonitors.com/products/mimo-720-SIt's USB powered (right, a single USB cable over to it), small 7" or so, and is a touchscreen. Works like a regular monitor
Here's a shot from Scott Hanselman's blog about it, extends the desktop just like a regular monitor

The non touchscreen version is 130$, the touchscreen is 220$ so it's not a steal, but that's pretty slick for an all in one solution