Now here's a concept that even Star Trek didn't venture into...and we'll probably see it within our lifetimes. Read the article, it goes into way more detail, but to summarize: Research is progressing rapidly at present working on systems where brainwave activity is monitored, interpreted and used to control computers.
Imagine a day when you simply walk up to an ATM and think your password...Viola! Money!
The researchers are working with monkey's now and they're seeing very promising results. Apparently, brainwaves are as unique as fingerprints, so it's almost a certainty that this will one day become a reality...sooner or later.
But here's my biggest problem with the idea, cool as it may be. This system could never be used for government level security. Because you wouldn't even need to torture someone to get them to give up their password. Just yell, "THINK YOUR PASSWORD...NOW!" And they'd do it.
Imagine telling people that they'd die if they thought about a purple elephant...the entire human race would keel over in seconds. It's just not possible. So unless we learn a way to not think about something...this would never work for really secure applications.