This may sound like a nutty idea, but please let me explain.
I run programming and electronics workshops for children and adults. I've worked with folks from 6yo to over 80yo. I currently use Arduino's. As an example, a significant fraction of adults who attended DEV8D came to my Arduino workshops last year, and this. They were all experienced programmers. The feedback was extremely positive. People really did enjoy writing programs to exert physical control on the world, even if only to blink a LED or buzz.
School children seem to enjoy it even more. There seem to be few opportunities for them to do something practical, especially something that is a bit crazy or unpredictable. Hence making a whining buzzer, or robot opens up a whole new world of programming experiences for them.
One of the things that seems to be attractive is 'bare-metal' control. I know I like it, and I don't think I am projecting that onto other people. Modern operating systems and applications seem to have disconnected programmers and programs from the hardware. Arduino has almost none of that, and I think people enjoy it that way. When folks want to, they can read all the source code for the libraries they commonly use, and understand it (in principle) with a bit of help in a few hours.
I'd like to use RaspberryPi as an embedded development board with a breakout board as discussed in this thread. I might prefer to use it with no software other than a loader and some basic hardware libraries. I realise I might need two, one for hosting and one as the embedded board At only £25, and a few £ for a breakout board that is fine with me. That is cheaper than an Arduino Mega.
So, has anyone done any experiments using RaspberryPi as a 'raw' piece of hardware, like an Arduino or Maple? Are all the device driver sources available, and do folks think they are practical starting points for building device support libraries (I realise it won't be "simples")?