Wish I hadn't ran out of time for this ... https://vimeo.com/mindhead. You can easily get to "on/off" with equipment like this. The rest depends on training protocols and the software design needed to implement them.
This is pretty cool, though probably a bit obtrusive for consumer applications. Also it doesn't look like the signal strength is that strong or varying (from what i can see in the video) which would make it pretty hard to try to fit equations that would match a specific actions induced from the brain.