I'm interested in the development of low cost EEG machines for personal use. I think it would be really interesting to develop biofeedback applications. It would also be interesting to develop classification algorithms to monitor your own sleep stages.
Hardware and software is available on the internet. All you've got to do is build it. This page contains my research in the development of EEG equipment.
Neural Prosthetics
The idea of neural prosthetics is pretty awesome. People with lost limbs controlling computerized parts with thought...just as if the machine is an extension of the person. Dan Morris: Neural Decoding Cyberkinetics - Neurotechnology Systems, Inc. Ambient Audeo is being developed to create a human-computer interface for communication without the need of physical motor control or speech production. Home - NeuroSky - brain-wave controlled games...very neat looking dry sensor headset..