After the touch-lamp and touchscreens, make sure to take a look at the touch-faucet:
I’d be interested to hear about other non-computer objects that have become controllable through touch-interaction in recent times.
Advancing Usability
On user interface design and the interactions between IT and society.
Advancing Usability 
Sometimes touch is useful, like shown here where you have soapy hands. As long as they don’t start deploying these in public washrooms and you have to touch it every second to keep the water flowing. 😉 I find those infrared faucets that turn off after 2 seconds and sometimes refuse to turn back on to be quite annoying.