RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.
DontPayFull - Verified coupons and discounts for a variety of online retailers.
Coupons.com - Coupons & Coupon Codes, Savings & Deals
Groupon - Each day Groupon offers a deal through local vendors in your city.
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
Dealspotr - Dealspotr is like Wikipedia for deals.