Here is the reference to the state machine framework for Arduino that I mentioned:
If our Arduino code and scheduler gets complex enough, a framework like this would be useful. And it is open source.
The other item I mentioned is the FPGA Cape for the Beagle Bone that I have just obtained. Take a look at the ValentFx site for more info: http://valentfx.com/
I will be going through the FPGA learning curve with this board (also open source). The ValentFx folks are real helpful and have been presenting at the NY Maker Faires.
Take a look at their site and some of the sample projects. For those not familiar with FPGAs, they provide digital logic that can be used to implement algorithms, etc. that are too computationally complex for real-time processing in software (especially small single board computers).
So projects like computer vision, sonar, underwater modems, become possible.