A simple web-app that keeps track of your github's followers. You can easily spot who followed or unfollowed you since your last visit.
The first time you enter nothing will happens... exciting right?? You will just be shown lists of followers and the people you follow. But in fact, under the hood, the tracking has started.
So the next time you visit the site, you can easily see all the changes that have happen.
As you guessed, "+" means new entries, and "-" means removed rentries AKA people who unfollowed you.
You can also click the "Save" button, for a new tracking to start from now on, and discard all previous changes.