[elhigh]

Slow down within reason. Get up to torque converter lockup speed, and then mosey along. The power needed to shove air out of your way increases exponentially as your speed rises linearly, so even a little slowdown yields big gains. But neither do you want anybody climbing over your backside because you're just a big moving speedbump.

Never stop. See that red light three blocks away? That's a long one, boy do you ever hate that pokey-slow light. If it's as long as that, no point in hurrying up to it, is there? Time it right and you're still moving when you get there - and there's some kinetic energy you didn't throw away, and don't have to burn more fuel to get back.

Those two are my favorites, but there's a sticky listing the 65+ things you can do and they all help. By the way - behavior modification is completely free.