Skyscanner - Skyscanner.com compares over 1000 airlines to find you the cheapest airfares, fast.
RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.
JetRadar - Compare flights from hundreds of airlines & travel agencies
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
Kiwi.com - Find and book the best low-cost flights all around the world
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.