GERTBOT - 

Gertbot Robotics Board - Raspberry Pi
What makes it so special? Gert has put an ARM cortex-M3 processor on board, which handles all the real-time requirements, so the Pi’s processor is left free to get on with other things – this means you only need to send high-level commands to the GertBot, and the board handles all the rest for you.

This is a powerful piece of kit. While Gert expects most of you to use it for driving motors and building robots, he notes that you can also use it to drive other things: using all three RGB channels, for example, your Pi with the GertBot attached can operate 30,000 led lights. Which should be enough for anybody.

And, of course, there’s the ability to generate DCC signals, which will make model train enthusiasts pink-cheeked and happy.