Environmental Economics reports that the EPA has recently published a list of their top 25 Green Power Partners (out of 607 organizations that participate in the program). The Green Power Partners are basically companies that are using electricity generated from renewable resources. From the EPA website:

Top 25 Partners are Partners whose annual green power purchase is the largest, and whose green power purchase has been completed. Their actions are helping drive the development of new renewable energy sources for electricity generation. Combined, their purchases amount to 3.3 million megawatt-hours (MWh) annually, which is approximately 75 percent of the green power commitments made by all Partners.

Interestingly, the amount of green energy used by the top 25 companies ranges from 2% of their total electricity purchase (Safeway) to 100% (Whole Foods, the World Bank Group, Advanced Micro Devices, WhiteWave, the Tower Company, Hyatt/DFW hotel, Western Washington University), with the average being 44% (but the median only 27%). Which leads me to wonder how much renewable energy the remaining 582 companies are using. But at least they're apparently trying.