The Epiphany onE puck (capital E is awkward but compulsory), can charge your iPhone using your beer or coffee.
One side is red and the other is blue. Place a hot drink on the red, or a cold on the blue, and you can charge your phone through the temperature given off.
It uses a Stirling engine to turn heat/cold into energy. US company Epiphany Labs has built a working prototype and hopes to have it on the market in 2014.
The company hasn't said how long it takes to charge and they're aiming to raise £63,000 on fund raising website Kickstarter to turn the prototype into a gadget that can be manufactured. They reckon it will cost £73 to buy.
"Once we have this project off the ground, we'll get to work on larger scale versions of the onE Puck that will provide inexpensive power to households and villages using nothing but waste heat as the energy input." The company said.
"There's nothing new about the idea of using Stirling engines to do that, but no one has ever successfully brought them to market in an affordable package."