I have a cash back AmEx card that gives me cash back. For the first $6,500 I spend in a year, I get like 1% on "everyday purchases" (gas, groceries, drugstore purchases) and 0.5% on everything else. After $6,500 spent in a year it jumps to 5% and 1.25%.
So at this point I just put everything on my card and pay it off at the end of the month. I'm averaging about $1,000 per month on the card so far. If I keep this up I should get back over $200 at the end of the year. That's not a huge amount of money, but it's easy money. The only effort I put forth is paying via credit card instead of debit or cash.
What would be nice is if I could somehow make my rent payments using my card. That's another $1,000 per month.