On the weekend I got pointed to an interesting Austrian company called Guger which offers biomedical sensor hardware and software solutions.
The g.BCIsys solution from Guger has some interesting applications that actually already work and are very valuable to paralyzed people.
A BCI cap that measures electrophysiological signals like the Electroencephalogram (EEG) or Electrocorticogram (ECoG) can be hooked up to a spelling software on a computer. Just thinking about a letter displays it and users can spell words just with their brain. Another solution connects a BCI to home automation. Users can open doors or operate the door communicator just by thinking.
There are some videos on the Guger site (Thanks Werner) that show these real world BCI applications in action.

We are still far away from the Matrix style brain plug, but it is astounding that BCI can be so very useful already.