RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.
Vouchertoday - Save money every day with the latest voucher codes, discount codes, and deals when you shop at your favorite stores. Updated daily and always working. 👍
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
Briefcase by AppSumo - "Netflix for software"
DontPayFull - Verified coupons and discounts for a variety of online retailers.