A Chrome Plugin
Capital One Shopping is a Chrome Plugin that monitors your online shopping to help you find coupons and locate the best prices. I put it to the test on Amazon, and within seconds it told me that my Logitech Brio webcam (the BEST webcam ever!) was $16 less if I bought it through Ebay.
Because I told Capital One my location and whether I had Amazon Prime for free shipping, the tool was able to calculate the overall savings after taxes and shipping were added in.
Watch this short demo to see it in action.