SteamAlerts - Track prices and receive alerts when Steam games go on sale
Savelist - Found products you want but not ready to buy?
SnapUp - Wireframe faster / create amazing user interfaces
LoveSales - Find and save products you love, get alerted when they go on sale.
PriceCute - Keep up with your competition's pricing on Amazon
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.