Fllwrs is a cool site for those of you who use twitter and would like to know who is following you and who is opting out. This is a cool service that is free and easy to sign up for. I have seen a few of the small businesses that I follow use this service and when people unsubscribe they ask why, and they send out a personalized thank you to those who newly subscribe. Very cool.
Do you use this service? If so what has your experience been?