I got $20 worth of gift cards in the mail today for doing three trial memberships at Complete Home, Live Well and Auto Advantage. It cost me a total of $3.
I already canceled two of those and I will cancel the other one tonight. Some of the offers have changed, but if you follow the directions given by Free Sample Freak here and here, and use the redemption links listed, you should be able to get the older offers. That's what I did. It took like a month for me to get these first gift cards and I am still waiting for the others. Even if I don't get them I am happy with Target gift card. $20 for only $3.
If you're going to try these out, make sure you follow Free Sample Freak's instructions.
I am not an affiliate of any of the sites listed. I don't guarantee that you will get the gift card. If you like to gamble go for it.