But there's more to running a sustainable enterprise than managing its appetite for pollution-generating commodities.

"We're not just talking about climate change and recycling and energy conservation," says William Blackburn, who runs a corporate sustainability consultancy. "We look across the board at environmental, social and economic issues together." A strategic approach to sustainability takes into account your company's impact on the communities it serves and operates in.

That may sound daunting, and more than a little hard to measure. But a program in Minneapolis suggests a brilliantly simple way to make a dent: instead of recycling old PCs as you refresh your hardware, donate them.

For the past two years, the city, in partnership with its desktop provider, Unisys, has turned over approximately 1,100 old PCs to a nonprofit called PCs for People, which refurbishes them and then gives them to low-income families. They're reusing equipment in a way that helps to sustain the community by advancing economic and educational opportunity for its residents. (The program won a 2011 Computerworld Honors award.)