Didnt read any other responses...but here are mine.

Save energy wherever you can. One thing that saves 50 cents every bill...well times that by 20 things and its another $10 off your bill, everything counts. CFL for house lights, be conscious of leaving lights and computers on, consider using your stove instead of your microwave, etc.

For the grow room, digital ballasts save a healthy amount of energy, especially when you consider that they produce more lumens so you can move down in watts but keep the same light intensity. Fan controllers to turn your fans down when temps are manageable. Use fluroescents for vegetative growth, and never run more then 18/6.