Originally built as a Quicken-competitor, Mint.com just became a lot more interesting. It's a case study in having aggressive terms of service that declare company ownership over data. When you own data, you can do a lot more than just provide a service to a web consumer.
Like make aggregate graphs like the above. Mint has direct access to the realtime spending habits of all their users. As such, they are able to forecast consumer spending *AND* revenues of large public companies sooner than everyone else. It's almost like insider trading. They will have information nobody else has access to. If you see Mint CEO Aaron Patzer making a killing on the stock market, I wonder if the SEC will come calling.
Mint proves that when it comes to making money with user-generated / user-provided content, opportunities can come in unexpected ways.