There's a lot you can do. Turn down the brightness on the TV's, draw the shades to compensate. Use a dark curtain during summer and a white, thermal curtain during winter to keep HVAC loads down. Put certain things on timers, unplug other things and throw them out (incandescent and halogen lamps, for a start). Make sure the house is sealed up tight against air leaks...
Heck, why not have a professional do an energy audit? It looks like it could pay for itself in a month in your case.
Also,
Ecofriendly DIY Home Projects .