As far as I know, surface EEG is almost useful in terms of controlling anything. It can even be quite hard not to make the software cheat and work with the much stronger and easier to control signals from muscles.

Stuff like that is useful for neurofeedback, however. I haven't tried the newer models of the Mindwave headset, but the older ones were easy to interface with over bluetooth. That's a place I might start rather than building a custom electronics board.