It seems so simple to me. and yet I'm a hypocrite, or at least not as thorough as I might seem.
Slow and easy acceleration uses less gas than punching it.
Braking is a waste of gas and brake pads. If I coast to a nice and easy roll then brake I've used gas to propel my car and not had to waste the energy by braking it away.
Speed -- each 5 mph over 60 mph increases the wind drag so much on the car the cost in gas is about 10 cents per gallon.
Other basics, decrease the amount of weight your car is hauling, decrease the wind resistance in any way posible, and paying attention to the road conditions so you aren't surprised by stop and go traffic all help immensely.
That said, this (250 Tips for improving gas mileage) is my new favorite webpage. It makes me look positively lazy about saving gas.
Of course, the fact that I drive a 4WD Subaru and not a hybrid or bio-deisel makes me look like a pissy snook about saving gas.
Yea sure, opinionated cardrivin'chick drives the next largest thing to a SUV, which ridiculously unnecessary size she complains about constantly.