Home energy ratings?

I read a recent bit about the burgeoning field of home energy raters related to the purchase of single family homes. Seems as if they're somewhat of a rage now with our ever-increasing energy prices. There's a non-profit called the Residential Energy Services Network that's doing some certifying and such of professional inspectors in the field. It's an interesting concept that might be worthwhile prior to buying a home rather than simply counting the number of windows or something. I would strongly consider it once you own a home too. Those monthly energy bills add up quickly and if $10 or $20 is saved you'll recoup the cost of inspection very quickly.