I picked one up last winter for my son's independent study. I bought the full-blown Cana-kit just so I didn't have to dig through the junkbox for the various parts. It came with the I/O ribbon cable, connector to breadboard PCB, power supply ... pretty much the works. He ended up doing a traffic light controller & used an IR tx/rx to detect presence (to speed up the time-out for the "side street" direction).

It's a pretty cool little system. The I/O is a bit limited ... but still a great little board. You can just plug in an HD monitor, USB mouse & keyboard ... and away you go.

If you want something that's a bit more rugged with more I/O options, take a look at BeagleBone Black. They're selling for about 55 USD these days.