We've already established that used coffee grounds can power radios, but before you have your morning cup of coffee, consider that those beans could be fashioned into an extra hand when squeezed into an airless balloon.
DARPA, who funded the project, claims it "could be on the market tomorrow", thanks to how easy it is to make. All you need is something to suck all the air out of the balloon which clumps the coffee grounds together. When attached to a mechanical arm (OK, not exactly something the average person has lying around their house, granted), the balloon can actually suck up objects and carry them without dropping.
Coffee is the perfect material for filling the balloon, apparently, as they're heavier and "are like lots of small gears... when they are not pressed together they can roll over each other and flow. When they are pressed together just a little bit, the teeth interlock, and they become solid." [PNAS via Hizook via BotJunkie via The Register]