Whole Foods is selling wind-power cards that looks like gift cards (with dollar amounts on them), but you can't actually use them to buy wind-generated (or any other kind of) power. In fact, the cards don't do anything but enrich an Enron-like energy broker called Renewable Choice Energy.
When you buy a card, you don't get any wind-generated electricity delivered to your home however. In fact, all you get is a card that doubles as a refrigerator magnet. Actually, you don't even get any credits, it's just a word they use to give you a sense of getting something from your money. The money you spend goes towards helping Renewable Choice Energy buy and sell electricity.
The cards are not even an investment, because you won't get any material value in return. It's all going to help another company get rich. Most companies seek investors to secure capital. But in this case, RCE is asking people for free money under the context of doing your part to help the environment. Link (VIA-boingboing)