If you sign up to receive $6 snack boxes from Graze.com, your first box is free with promo code invite10. You must sign up for a subscription and give your credit card number. The default is a shipment every two weeks but you may change it to every four weeks which will give you extra time to cancel if you wish. You may cancel at any time using their web site.There are 95 different snacks they offer, but they send you four snacks per box. On the web site indicate which snacks you prefer, which you do not want, and they will make up a custom box to send you. Each box is $6 including USPS shipping.

http://www.graze.com/us/
promo code = invite10

Note: You do have to give a credit card to sign up.

Note: You can easily cancel your membership as soon as you get the free box, and therefore not have to pay anything to them, but make sure to check out the rules before you sign up and know what you are getting into, since this is a service that sends out boxes of snacks every two weeks then charges your card.

See similar offer from November here:
http://www.fatwallet.com/forums/free-stuff/1314543/