I am sure my husband is shivering at the thought of this, but turn off the plasma or LCD and use an older or smaller tv. Your old tube tv is going to use less energy than any newer tv and the smaller that tv, the less energy it will use. Take a look at the annual energy costs different types of tvs have: http://cybernetnews.com/2007/10/15/cybernoteshow-much-energy-does-your-tv-consume/
I hate to admit that we have a Plasma. I wasn't educated about the costs associated with a plasma when my husband convinced me that was the tv we needed to buy. So, how does one correct that? Well, I limit the amount of tv watched on it during the day and encourage my daughter to watch programs on the small 13” tube tv we have. Unfortunately, the DVR is hooked up tot he plasma, so most of our evening television watching is on there.