I just had a really freaky idea.
Suppose, using a few of the digital IO ports on the robot controller, one was able to implement the USB specification, which is outlined at
http://en.wikipedia.org/wiki/USB#Technical_details and written in detail at
http://www.usb.org/developers/docs/
Besides being wicked cool, it may serve as an interesting method for new input devices (imagine dead-reckoning with a mouse?)
As far as I know, a USB port would only take up 4 DigIO ports, so if you were to add a non-powered USB Hub in there you could have... man, that would just be cool.
Just throwing ideas out there. What do you guys think? Doable on the hardware provided, or would the requirements be too large?