Electronic Design magazine is running a short tutorial on the Controller Area Network (CAN) standard and associated protocols such as CANopen. We posted a link to a longer tutorial about a year ago, but it's always good to have a refresher course once in a while. You can find a CAN port on robotics-oriented microcontrollers such as the New Micros IsoPod. For a good example of what you can you do with CAN, check out Mike Keesling's CANipede.