Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
Price Snoop - When viewing a product on Amazon, Price Snoop will show you just how much it costs on the other...
PriceSpy - PriceSpy helps you save money when shopping online.
Shoptimate - Use the Shoptimate extensions to compare the price without any click. When you browse an item on a online store, a bar shows up at the top to tell you if the exact same item can be found cheaper elsewhere. Including shipping costs
Savelist - Found products you want but not ready to buy?
Prisync - Prisync is a competitor price tracking and monitoring software for all sizes of e-commerce companies worldwide.