I just did it and I hope you will, too. I joined Temple Sinai's WIN/Clean Currents partnership. The temple gets a $20 donation, you get electricity sourced from renewable (wind) producers and you show your support for the Sinai-WIN partnership.
Get out your PEPCO Bill (you'll need the account number) and click here: http://www.cleancurrents.com/index.php/win-green