Sure, some of the information is useless, but if you like statistics and love to analyze things, 'Friday' will probably end up installed on your phone. And if you didn't know that it was downloaded on your handset, you would never know except if you stare at the notification bar after a call or text. Otherwise, 'Friday' is quiet.
The app is free, but you need to be approved for the Alpha release for it to start working. Simply installing the app without this approval will not work. To sign up for 'Friday' and ask for approval, simply click on this link.