Foc.us is a company that makes headsets for gamers. Those headsets, starting to ship in July, send electricity through your brain. This is their pitch:

If that sounds a little sketchy to you, that's because it probably should.

The excellent NeuroBollocks blog explains how transcranial direct current stimulation (TDCS) is an interesting idea: sending targeted, low-level electric currents through the brain with TDCS excites certain regions, which could have implications in treating depression and stroke victims.