For you folks in the TVA (Tennessee Valley Authority) service area, here's a free online energy audit. It's fairly detailed, and the more information you provide the better recommendations it can make. Complete it by the end of June 2008 and get a free home energy savings kit complete with some CFL bulbs and other goodies.
You can enter up to 12 months of utility bill info, but I put in just two, one for August and one for February. It did a pretty good projection on the other months based on that. Anyway, have a couple of utility bills handy when you start the survey. (P.S. The survey asks for gas consumption in "therms." Ours is billed in CCF. The conversion factor is 1 CCF = 1.0250 therms. Or you can just enter the CCF and it's close enough.)
Bonus: If you register and complete the survey, TVA will send you an energy conservation kit that includes two compact fluorescent light bulbs, outlet and light switch gaskets, filter whistle, two faucet aerators, hot water temperature gauge, home thermometer, and a "How to Save" brochure. (Through June 30, 2008, while supplies last.) That's a pretty good deal.