Although winter is still a ways off, Microsoft Research has proposed a novel idea: install a computer server where a heater would normally go. The exhaust air from servers is between 104 to 122 degrees Fahrenheit:
Channeling that excess heat could turn a regular old server into a “data furnace” that keeps homeowners warm in the winter, dries their clothes and heats their shower water. … Data centers use loads of electricity, and they’re only going to use more as more people stream and download more movies and music. But at least in the United States heating uses even more energy (6 percent of the national total, according to the Department of Energy) than servers do (3 percent). If servers doubled as heaters, we’d be getting the same services for half the energy cost.
The Dish 