I pay for everything; food, clothes, gas and whatever will take payment with with my Amex card. I even pay my car insurance and cable online with it.
Because Amex has to be paid in full every month, I dont carry any debt and I don't pay ANY interest or fees for using that card, only an annual fee of $45.00
I have racked up lots of points (they add up rather quickly) and my family and I have traveled many, many times on free tickets from that card. I just book the tickets in their website and they deduct the points from what I have accumulated for payment. I can also transfer the points into my frequent miles accounts (Continental, Delta, ect) to purchase tickets. I can also use the points for buying merchandise from their catalog or getting gift certificates for restaurants, stores and even for theater tickets!
I also have my debit/bank card which also gives me points every time I use it. On certain purchases, they have double miles promotions (two points for every dollar you spend). Last month I used my accumulated points to get a $ 250.00 gift certificate for a store and bought a WII game system for my son.
Using credit cards smartly is a great tool to get free stuff!