1) Water pressure. High water pressure showers and faucets not only use more water but stress your fixtures as well.
2) Leaky faucets, of course, are most common. Little drips that seem irrelevant can waste over 50 gallons a day. That's over eighteen thousand gallons of water a year. Not only are newer faucets better looking, they are also more efficient.
3) Toilets. Most toilets are out of date. One way to see if your toilet has a leak; Put some dye or powdered cool aid in the "tank" and see if it colors the bowl water after twenty minutes or so.