Jungle Scout - Amazon product research made easy.

RetailMenot - The RetailMeNot mobile app allows you to find deals on the go for both online shopping and in store shopping.

Inventory Spy - Spy how many products remain on any Amazon Product’s offer listing page.

Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything

AMZScout - AMZScout extension will help you make a decision about picking a niche based on the actual data, not intuition.

Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.