Frequently it makes sense to replace an inefficient device with an efficient one or purchase helpful items that will quickly pay for themselves in energy and/or water savings:

• Replace incandescent bulbs with compact fluorescents or LED bulbs whenever practical.  Pay special attention to the bulbs that get the most use, including porch lights, night lights, bathroom vanity lights, etc.  Here in Arizona, efficient lights will save directly on electricity AND will save on cooling costs, because so much energy is wasted as heat in incandescent bulbs.  Mercury fears in CFLs are overblown, and bulb recycling boxes are now easily found at many retailers, like Home Depot, IKEA, etc.
• Place electronics on power strips and/or "smart" power strips to reduce vampire power.  See my "products" page for more on Smart Strips. 
• Replace faucet aerators with "watersense" labeled low-flow versions.  Most modern faucets have 2.2gpm aerators installed.  I've had good luck with a 1.5 gpm model I bought at Lowes for $3.75.   Aerators are available with flow rates as low as .5 gallons per minute(gpm), but they tend to splash a lot due to fine sprays and high velocity.  You may have been annoyed by these in public restrooms.
• Replace your showerheads with "watersense" labeled units.  The less hot water you use, the less energy it takes to heat it.  Municipalities also use a tremendous amount of energy treating and transporting water.  There's an entry on my Links page for an online retailer that carries a model I like called "Earth Massage 1.5 GPM".
• If you own a decent toaster oven, try to use it or the microwave instead of your large oven or stove top.  Convection ovens(either toaster or full size) are more efficient.  An electric kettle is a very efficient way to boil just the right amount of water for various cooking needs.