Google Trends

The new Google Trends tool is pretty cool. You can use it to compare the relative popularity of competing services, products, teams, etc. Similar to Google Finance, the graphs include related news stories as reference points. Here are some examples:

Yankees versus Red Sox

Pepsi versus Coke

iTunes versus Napster

Yahoo versus Google

XM versus Sirius

Flickr vs Shutterfly vs Ofoto vs Snapfish