It's easy to sign up for all the free trials, but normally not so easy to quit. So if you're struggling shutting of your new Amazon Prime free trial because you don't want to fork over $79.
You can manage your Amazon Prime settings by going down the lefthand navigation into Amazon Exclusives. Then click the orange manage my membership button in the lower right. Then click the Do Not Upgrade button and turn off auto upgrade.
So now you got some free 2 day shipping even if you're not interested in Amazon Prime. Thanks Amazon :)