The one beautiful thing that cardpool can do that cash cant do is get you a discount without having to bargain. All you need is a little bit of foresight.

When I was going to buy my Droid X, I knew BestBuy was going to be selling it so I went on cardpool and bought two 100$ cards and got 6% off of 200 from the phone. Its a great service if you know your going to spend the money and want to reward yourself for planning ahead.