Savelist - Found products you want but not ready to buy?
Slickdeals.net - Slickdeals: The Best Deals, Coupons & Discounts on everything
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
BrickSeek - BrickSeek is a web application designed to help you buy those "Hard To Find" Lego Sets at...
LoveSales - Find and save products you love, get alerted when they go on sale.
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.