If you’re in the market for a used car, then check out They don’t sell cars, but they do allow you to perform a search that covers multiple car sites and it plots the results on a graph where the vertical axis is the price and the horizontal is how many miles are on the car. It also features what I might call a trend line that shows you the price trend for cars of various mileages. I found this to be overly useful since it allowed me to quickly spot bargains because they appeared and icons that were much lower than the trend line (just hover over an icon to see a pop-up that indicates the mileage and price for the car and a photo if it’s available). It also made it easier to compare two car models to get a real sense for the cost difference without having to browse through dozens of individual web sites.