Google Checkout Trends: Google knows where you shop, what you buy
Now, it's not quite as bad as it sounds. Google is anonymizing the data before releasing it. So there's no way you can use this tool to find out what Steve from the office bought his wife for their anniversary. Not yet anyway. But you can get a picture of what items are popular over time, and how two items compare with one another. For example, you can search for "ipod, zune" to see which item sold better last month.
Or at least that's how it works in theory. Right now the service seems to be down. Ionut Alex Chitu at Google Operating System grabbed a screenshot of the service last night showing that it must have worked at some point. But even Google's suggested searches return no results right now. Let us know if you have any better results in the comments.
[via Official Google Checkout Blog]