WishSimply - Wishsimply is a easy-to-use online and mobile service to manage and share your wish lists.
Keepa - Price history charts and the option to be alerted on price drops for all Amazon sites.
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
Shopping.com - Shopping.com is a leading price comparison site that allows you shop online for the best deals and lowest prices. You can read unbiased product reviews and compare prices online. Online shopping has never been as easy!
WishMindr - WishMindr is a free online service that allows users to create gift wishlists for birthdays...
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.