Do any of you know of any good, reputable companies that offer credit cards with good reward programs, preferably cashback?

I figure I spend so much money on gas each month, if there was a way to get something back for using a credit card each time (and then paying it off each month instead of each time at the pump), I could save a lot of money.

So… any good’uns?

Oh, and something that doesn’t expire in three months or six months woudl be nice. Something that doesn’t go away.

update: I just got a Discover Platinum Gas Card, which has a 5% cashback “bonus” on all gas purchases (well, actually it’s only for the first $1500 in gas purchases each year. Then 3% for the next $1500, and finally 1% for everything over $3000. But, I don’t figure that’s going to be an issue for me). 1% on all other purchases.

How Duke gets students.