Flit: Search for a specific item across all your favorite online shops at once. You can then compare prices side by side. And best of all.... it's free!
Snapette: Using your current location, it shows you photos of items near you as well as the best sales in your area. It's another free one.
Hukkster.com: Join for the ability to "Hukk" or save to your list any product you see while shopping online. Hukkster will then notify you when the product goes on sale. You can learn more about Hukkster from this report by Amy Buckman.