About 5 percent of the energy consumed in the US is from electronics that are still sucking your power when they're turned off or in sleep mode. This costs people about $3 billion. A plasma TV can cost you $160 alone each year. A DVD player: $9. A desktop computer: $35. The clock on the microwave: $3.85.
Now they sell power strips that will basically shut off all power to peripherals when the TV or computer is not in use. So if you shut off the TV, it'll kill the electricity to the DVD player, and the stereo receiver, etc. If you use it on the computer, it'll shut off power to the monitor, printer, speakers, etc., when not in use.
In the long run, these power strips will save you money--and they're just one of many examples of how simple energy efficiency can dramatically reduce our energy needs and carbon footprint.
Hypocrisy meter: I'm mid- to high-range on the hypocrisy meter for this one. I turn cut off the power to most of my computer peripherals, though I do leave the modem and router on (which I shouldn't do). My old TV doesn't suck power when it's off, but I don't cut the electricity to the DVD player when it's not in use. I've been meaning to get some of those power strips, like this one. It's about time I finally did it.