Search for products on: Google, Yahoo, PriceGrabber, Shopzilla, Amazon, Buy.com, etc. and kulist.com will show you price comparisons directly into your current page.
Click on a merchant for any product and optionally add the product to your "lists".
Travel site that searches and compares travel fares and travel deals from over 100 sites. It also provides shopping interface to shop more than 20,000 travel products. Uses eCommerce APIs from Amazon...