That reminded me: Dreamhost (http://dreamhost.net) is a green hosting provider, they buy carbon offset credits for all the CO2 their data center produces (estimated, no doubt).

http://www.co2stats.com/

For example, we use Bullfrog Power, which is available in parts of Canada. If our power consumption is e.g. 100kW, they’ll purchase 100kW of power from an eco-friendly wind power provider, which is fed into the grid. Net result, that’s 100kW less of coal-based or oil-based power being generated and fed into the grid, with all the environmental benefits that provides.

If that’s not your speed (actually, even if it is), you can rarely go wrong by reducing consumption. When your bulbs die, replace most of them with compact-flourescent (CFL). Use task lighting rather that illuminating your entire room.

Use LCD monitors for your displays, and make sure power-saving features of your computers are properly configured. Don’t stop at setting the time for your display and disks to sleep, make sure that processor power-scaling is available and working — that way, your CPU won’t draw as much power when its full capabilities aren’t needed.

Using a lower-end video card in your work computer will help as well — gaming-quality video cards draw incredible amounts of power, and produce quite a bit of heat (which you have to spend power in terms of fans and possibly A/C removing).

Keep an eye on peripheral usage — do you really need your printer on right now? What about your webcam? Anything plugged into that powered USB hub? Don’t forget that your power usage goes up when you plug USB devices in, whether or not you’re using a powered hub.

When possible, use a corded phone — the power for such phones is transmitted on the telephone line, and is significantly less (in most cases) than what’s pulled to operate (not to mention charge!) a cordless phone. In fact, avoiding wireless peripherals (like Bluetooth mice) will often have a decidedly positive effect on your power consumption.