There's an article about the creators on Seattle 2.0 - http://www.seattle20.com/blog/Startup-Profile-TweetSum.aspx
Plus, from what I know about the project it's not something they're trying to make money on
Here are some gems.
- In addition, from time to time we may collect personal information that you provide in connection with participation in surveys, sweepstakes, contests, games, promotional offers, and other activities on the Site.
- we also will collect your credit card and billing information.
- contact you about our or a third party's services, products, activities, special events or offers
Given the tone of what they plan to do with your information once they've collected it, this isn't a site I'd sign up for.