Go to energizect.com and click on "Supplier Rate FInder"

This will show you all of the alternative and their rates, lock-in periods, and REC percentage.

I chose Think Energy, and it was as simple as clicking the Enroll link, and filling out a form. I had to look closely at my bill to find some of the thinks they needed like billing cycle and name key, but it took all of 5 minutes.