In one of the best "green tips" article I've ever seen, the NYTimes interviews Eric Corey Freed to find out the 5 best steps to a green home that anyone can do. My particular favorites (and ones I use) are the programmable thermostat and the power strip to avoid vampire power sucking.
We've got a programmable thermostat here in the home where I live. I actually bought and installed it myself; it was super easy to do (I followed some tutorial online; just google and look around until you find one with pictures that makes sense), and I've been quite pleased with it. Mine has three settings for every day: "sleep," "awake," and "away." Technically, I think you can make four settings by having different awake temps in the morning and evening. Because our basement is cold, we only turn our temp down to 60 at night, but it's 60 or 58 during the day while we're at work. We do go up to 66 in the morning and the evening, and sometimes my roommates turn it higher when I'm not home (I'm the real stickler on the thermostat). I know one of my roommates uses a small space heater in her room, but that's still cheaper than heating the whole house. I really enjoy having one to take the thought out of reducing your energy load.
The power strip thing is something I pursued more aggressively last year, when my roommate and I turned off everything (TV, microwave, etc) when not in use. We actually saw a difference in our power bill! And, from anecdotal evidence from friends, I've heard that turning off your computers overnight also results in some big energy savings. My proudest electric saving ever came last summer, when I rarely turned on lights (yay for natural lighting), didn't use the dishwasher, and actively tried to conserve power. I got my power bill down to $15 for one month, and this was when I was paying extra money on my bill in order to support renewable energy.
I like the other initiatives listed (low flow shower head, grey water recycling, and less water per flush), but they're a bit more intense than what I've done already. I keep meaning to look more into an ultra-low flow shower head, and I would love to someday do grey water recycling for all the water in my house except toilets.
Perhaps my favorite thing of all about these green tips is that they will all ultimately save you money. A few of them have higher start up costs, but most of them are cheap to do and will save you money within a few months. Nothing better, in my mind, than being kind to the environment and to our wallets at the same time.