Using several microcontrollers as nodes in a neural network
Depending on the application, it would certainly be a possibility. The problem I foresee however, is that for an effective neural network, it needs to be trained via back propogation. Typical ATTiny is something like 20Mhz, whereas a computer is 2Ghz+. Training the neural network would require significantly more time due to the much lower processing speed. Which isn't to say it isn't possible, but you would have to carefully examine the application of your neural network before implementing it. It's also an Idea I've had for a while regarding robotics sensory, localization and path planning. Rather than programming a bunch of rules about how to move in an environment, have sensory input act as the inputs to neurons, which then teach the robot how best to interpret data to get to a destination.