I have a credit card that’s so good, you can’t even get it anymore. My Schwab Invest First Visa gives me 2% cash back on everything that I buy. That’s like getting a 2% discount on everything. The deal was so good, and attracted so many people who like to game the system (like me) that they closed it to new applications. They are, *for now*, continuing the same rewards.
Responsible use of a credit card can accumulate some nice rewards. I find cash back to be the easiest, but there are also cards out there for airlines, amtrak, hotels, etc. Google to find websites that compare all of the best current deals.
American Express, Chase, Discover, and BoA all have cash back cards. Pretty much every airline has a credit card, and American Airlines and Southwest are two of the most popular. I’ve also heard that the Amtrak card is good, and points are transferable to Continental Airlines.