"Neurofeedback" already exists it's just still under the radar (it's like teaching yourself to roll your tongue). I've been trying to pull some demos together to demonstrate that the web browser is the place this will take off: http://vimeo.com/32059038 (sorry I haven't pushed more of this extra-rough demo code yet). Consider using something like the wireless PendantEEG if you're going to be doing your own development OR be prepared to pay excessive licensing fees required from a few of the vendors mentioned here. If you are interested in helping develop this stuff mentioned in that video (and don't mind springing for some reasonbly cheap hardware) please ping me. I'd also like to plan a MindHead hackathon/mini-conference this spring in Boston (my personal interests are improving attention and relaxation, peak perfomance, and BCI).