Plasmas are terrible for power consumption... you don't even have to hook up a meter to one to tell that much, just stand about 3 feet away and you can feel the heat off 'em.
LCDs aren't that great either... and some of the fancy "eco" LED ones actually draw
more power than comparable CCFL-backlit units. The 42" Hitachi LED unit we have here pulls about 130W on a pretty low brightness setting.
OTOH, I picked up a 2004-ish 52" CRT rear-projection HDTV off the side of the road a year or so ago, and fixed it up for a friend. Out of curiosity I hooked it up to the Kill-A-Watt and could hardly believe the reading I got... it was something like 65W.
