PC World on a nifty little $2.50 gadget called the Batteriser, which is designed to extend the lifespan of disposable batteries by 800 percent:

Voltage boosters are nothing new, but Batteriser scales down the technology to the point where it can fit inside a stainless steel sleeve less than 0.1 mm thick. Roohparvar says the sleeves are thin enough to fit inside almost every battery compartment imaginable, and the combined package can extend battery life between 4.9x for devices like remote controls and 9.1x for various electronic toys.

“The Batteriser has boost circuitry that will boost the voltage from 0.6 volts to 1.5 volts and will maintain voltage at 1.5—which is a brand new battery,” Roohparvar says. “There’s actually no IP [intellectual property] in the boost circuitry. Our technology is really a miniaturization technique that allows us to build the sleeve. We have some IP in some of the IC circuits that are in there, but the key is we’ve been able to miniaturize the boost circuit to a point that no one else has been able to achieve. “

Quite cool, assuming it’s not snake oil.