Sam's Club Hack
If you shop at Sam's Club you are probably aware that they only take cash, checks, debit cards, and Discover.
If you spend $3,000 a year or less it is NOT worth it to sign up for a Sam's Club Discover versus your traditional Discover.
Chase debit cards will give you one point (~$1) for every $4 in purchases for a .25% return. Citi will do 1 point for every $3 in purchaes for a .33% return. Normal Discover cards will give you .25% back plus the float at 4.75% for thirty days gives you another .14%.
However, if you shop regularly at Walmart there is a better solution. Buy gift cards that you will use in the next two months with a 1% cash back card and use those gift cards at Sam's Club (they will say Walmart gift cards but you can ask the people if they will work at Sam's and the cards even mention Sam's on the back of the card) and you will come out ahead. If you were smart enough to get a Bank of America Power Rewards card, you can get 2% back and come out way ahead. I estimate since I go to walmart anyway (don't make a special trip or you'll kill your savings in gas) I save almost $4/month this way for no additional effort (I was already in the checkout line at Walmart anyway).