Listinguish - Listinguish, the easiest way to increase your e-commerce sales.
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
Minderest - Leading price intelligence and competitor monitoring tool for retailers and manufacturers. Learn your competitors pricing strategies and increase your profits
Fetchee - Fetchee is a free price tracking wish list app that works with all online stores worldwide.
LogiPrice - LogiPrice monitors the price of your competitors or any online retailer.
Keepa - Price history charts and the option to be alerted on price drops for all Amazon sites.