Wikibuy - Find lower prices at other sellers while you shop on Amazon
OctoShop for Chrome - Compare prices and get alerts when things are back in-stock
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.
HotStock - HotStock is an all-in-one real-time product tracker for you that allows you to find the right product, exclusive deals, and discounts from all the major online stores.
CouponFollow Cently - Coupons at Checkout is a browser plugin for Chrome, Firefox, Internet Explorer, and Safari that...
LineScouts - Rate queues in stores to keep the vulnerable safe.