Google Checkout Trends reveals the sales data of merchants in Google's Checkout sales network. Google Checkout Trends helps webmasters to get an idea about the success of products. Here is the link- http://checkout.google.com/trends
Coolslko, Thanks for sharing the info. That is a good tool. You can compare searches more than two words or phrases by separating with commas.
But Google Checkout works not in all countries and can't compete, for example, with PayPal, 2checkout and others
Google Trends allows you to enter keywords and phrases to compare what users have been searching for over a specified time period. It lets you see what people have been buying using Google Checkout: For more information Google Trend Lab