This board seems interesting
http://www.raspberrypi.org/gertbot-is-here/
This board, apart from the Raspberry direct interface, is rs232 driven, so may be interesting also for .netmf interfacing to use various motor applications. It’s a pity that it uses an Atmel Cortex-M3 chip on board with not-user-programmable firmware (no public domain).
Also interesting:
“or example, your Pi with the GertBot attached can operate 30,000 led lights. Which should be enough for anybody.”
I think @ Devhammer might disagree as to how many blinky LEDs are “enough” 
Pete
30,000?
Pfft! How are you going to make a robotic jumbotron with only 30,000 LEDs?
@ devhammer - but you can chain 4 boards so … 120000 is near to enough also for mazinga z.
I think you can hav good price for 120000 LEDs batch
