Electric Bill Rules of Thumb

I've been thinking about energy usage recently. Turns out that if you take wattage and pretend it's dollars, that's approximately your annual cost for leaving a device on 24/7. So a 50W LCD panel costs $50/year. I have two servers, a PC, some really big powered speakers, so I'm rather curious how I might use less electricity. This is assuming 12c/kWh of electricity.

Also, after some websurfing I bought a Kill a Watt device from smarthome.com. Haven't tried it yet.