Twitter is a great micro blogging service and if you have large number of followers on Twitter, you never know when someone decides to unfollow you. Qwitter is a new web service which allows you to get notified when someone unfollows you in Twitter. Qwitter will send an email notification when your account loses a follower.
Another good thing about Qwitter is that it gives email notification along with your last tweet when some body has decided to unfollow you. Qwitter does not require your Twitter password for sending the notification, it only need your Twitter username and the email address where the notifications are sent.
In case you wish to stop using the service, you can do it by clicking the unsubscribe link at the bottom of the notification mail sent out from Qwitter.