My local public utility district sent a postcard offering a free low-flow shower head and faucet aerator. The shower head lowered the flow from 2.5 gal/min to 2.0 gal/min. The difference in the shower wasn't too noticeable. The wife's not too impressed with the sink aerator yet.
As I mentioned in an earlier post, I turn the shower on to full-blast hot when warming up the shower. If I'm shaving, I turn on the hot water for brushing my teeth. It still takes probably 10 seconds to get mildly warm water. Instead of letting it go down the drain I've started filling up a container. Between warming up the shower and the sink for shaving, it adds up to more than a half gallon. I've been using the water to refill the toilet tank. Probably not for everyone, but the water could be used for plants, your coffee pot or your Brita water pitcher.