Priority Unfollow
I just put together a few lines of code to help you unfollow those who are most likely never to follow back. There's no complicated algorithm to do this. Currently, I'm just checking to see if the number of followers of a user is greater than the number of friends.
When you click the link 'Priority Unfollow', all those users who have more 'friends' than 'followers' would be hidden. You can then start unfollowing all the so called 'twitter celebs' i.e. users with a large number of followers but very little people they follow back.
This feature is currently available only for JustUnfollow Premium users. I may make it available to everyone but I can't commit on it. You can opt for JustUnfollow Premium at just $4.95 per year.
