We use a thermos for keeping coffee warm instead of keeping the pot plugged in.
Wind-up alarm clocks.
Rechargable battery operated wall clocks.
Using the sleep-mode on our TV where it will automatically go off after an hour.
Clothesline for outside & dryer rack for inside.
Not gadgets but -
a)Opening blinds/curtains/drapes for light during the day, which should be a no-brainer but, I've had to work w/my kids on this one to keep them from just automatically flipping a switch.
b)Opening 2 or more windows for a cross-current to keep cool.
c)Putting on more winter-weather clothes/hats to keep warm rather than upping the thermostat. Reverse that in summertime to taking off some clothes or lighter weight cotton clothes to cool down.
d)In the spring & summer I sometimes go outside w/my head wet and dry my hair by standing over the air-conditioning unit where it blows out hot air. Much faster than a blow dryer!
You might want to check out:
Real Goods - Solar and Renewable Energy - Eco Household and Products for Green Living