Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
Domcomp - No-nonsense domain price comparisons, updated daily
PriceSpy - PriceSpy helps you save money when shopping online.
Savings.com - Compare prices at local stores & discover the best deals
Savelist - Found products you want but not ready to buy?
PriceCute - Keep up with your competition's pricing on Amazon