BCI

A recent news story reports on what is quickly becoming more than just a fantasy solution:

Brunner and two colleagues from the state-financed Wadsworth Center in Albany, New York were demonstrating a "brain computer interface (BCI)," an astounding technology which digitalizes brain signals emitted as electrical impulses -- picked up by the electrodes -- to convey intent.

If your product's user interface requirements don't allow for this (or this) sort of psychokinesis, you've ventured too far into design.