Groupon

Groupon offers great deals on the best things to do, see, eat, and buy in your city. Every day, Groupon.com offers a different deal on something great. If you see a deal you like on Groupon.com, just click “buy” and if the minimum amount of people sign up for the deal, your credit card will be automatically billed and a link to the Groupon coupon will be sent to you. If the minimum amount is not met, then the deal is cancelled and you’re not charged.

http://www.groupon.com