Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
AmzScope - Find profitable products for sale on Amazon in one click, relying on statistics instead of intuition
PriceSpy - PriceSpy helps you save money when shopping online.
Inventory Spy - Spy how many products remain on any Amazon Product’s offer listing page.
Savelist - Found products you want but not ready to buy?
ProfitGuru - ProfitGuru is the easiest way to find the most profits on Amazon.