A couple of engineer buddies have designed the latest must-have accessory for the coffee drinker. Joulies are metallic beans you drop into your hot cup of coffee to make it exactly 140 degrees. They haven't even been manufactured yet, but already the project has accumulated some $35,000 in Kickstarter cash. I guess a lot of people are tired of blistered tongues.

Each Joulie is a small metal shell filled with a phase-change material that melts at 140º Fahrenheit. (Some people might prefer 155º -- perhaps there will be a version for us.) So the Joulies absorb heat from the coffee till they reach 140º, and then start emitting heat. The effect (if you put in enough Joulies for your volume of beverage) is to maintain the coffee at the desired temperature for long enough to savor it. Using an insulated cup is recommended also.

We've seen this idea before, in the form of Fraunhofer's Perfect Coffee Mug, but this time it seems poised to actually come out of the lab and into your cup.