When going on vacation, don't forget to turn the central water valve off to your home. This will minimize any damage if you have a plumbing problem. To save energy, you might also want to turn down the thermostat on your water heater. But don't turn off the heat. Leave the thermostat at a low setting.
Other vacation hints:
Put a few lights on timers throughout the house.
Stop mail and newspaper delivery or ask a neighbor to collect them while you're gone.