I installed a Kill-o-watt meter in my home theater probably a year or more ago, and just now read the meter while pulling all the gear out for our move.
The readings were:
1094 hours time
71.03 kwh total used.
That doesn't seem to compute for the year I had it in, but more than likely it resets whenever the power fails, which happens from time to time down here in Florida.
So, in the past 1094 hours (or 45 days) I used about $7.00 of electricity, or about $5 a month for a 61" LED RPTV Samsung (HLT model), PS3, Xbox 360, Harmon-Kardon HK635 amplifier and a monster power conditioner. Not bad price for the electricity, really, and I would have guessed higher. But it is only used really for movies, and not used as frequently as the family room plasma which is powered on more frequently.