Cut Your Electric Bills

Unplug the electronic appliances when you aren't using them. Everything is either on, or on standby these days.
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Plug your things (like TVs, video game consoles, satellite receivers, etc) into a power strip and turn it off when you're not using it.
Turn off anything you're not using (like a TV on as background noise, a radio in the other room, a video game that's been paused for an hour, fans in rooms that you're not in, etc), not just lights.
Turn up the thermostat, as has already been said.
When you charge your cell phone, unplug it as soon as it's done charging. It'll continue to draw power even when it's done (especially if yours is like mine and it stays lit up while it's plugged in).
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It's great that you ask. In addition to cutting down your bill, you are also doing something healthy for the environment.

Let's start with the easy stuff:

Light bulbs – make sure you're using compact fluorescent bulbs everywhere. They cost more to buy, but last much longer than regular bulbs and take less energy. Basically, they pay for themselves. But if you aren't ready to replace every bulb in your home, start out by making a commitment to change the lights you use most often, like the lamp on your nightstand or the lights in your living room.

Drafts – You would be shocked at how much energy you use heating and cooling the outdoors! Make sure all windows and doors are tightly insulated. Doors are easy to check. Just crouch down at floor level during the day and see if any sunlight shines through. If it does, the weather stripping needs to be replaced. It's very cheap to buy at the store and takes about 2 minutes to re-apply. The savings of plugging leaks are substantial!

Appliances – As other people have mentioned, appliances and electronics use up a lot of energy, even when they don't appear to be "on". We had a coffee maker with built in clock that ran 24/7. What a waste! We rarely even make coffee! So we unplug it whenever it isn't being used. Computers also take a lot of energy. Instead of putting it in standby mode at night, turn it off completely. You can't check your e-mail while you sleep, so why pay for all the extra energy?

Thermostat – Turn the temperature up 1 degree every few days, to give yourself time to adjust. If you do it gradually, your body will adapt and you won't even sweat. We actually keep our A/C set to 78 degrees downstairs. Hard to believe, but we never even notice because we did it gradually. If we do get a bit warm, we use a ceiling fan and that usually works. Also, make sure to use heavy blinds or curtains when the sun is shining in. That makes a big difference.

Speaking of adjusting the temperature, turn it up even more when you are gone during the day. If you have pets, they will be fine, assuming you don't have it set to something absurd like 90 degrees in your home. But you could probably even get away with 80 degrees. Why pay to cool down your furniture, right?
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