The HAL-5 exoskeleton suit is nearing "mass" production. Engadget reports that professor Yoshiyuki Sankai at Tsukuba University is hoping to have the suit ready for 400-500 units by 2008, with a mere 20 units produced in 2007. The suite allows its user to double his lifting abilities.
It operates by sensing weak electrical impulses from muscles via electrodes on operator's skin and sending them to the onboard computer which in turn analyzes them and activates corresponding servos of the suit, mimicking wearer's motions. [Via
Wikipedia ]
You can read more about the HAL suit, and the 10 years of work that's gone into it, in
this New Scientist article. There's also more information about HAL on it's website. A HAL suit of your own will set you back about $40,000 USD or $600 a month to rent.