Obviously, as everyone needs to remove followers in relation to other Twitterers that are being followed:
a) Is it a good idea to "block" those that are unresponsive OR simply "unfollow" them? If you block, then whenever you seem them again they are flagged as a "block" (and you can reassign) but when you "unfollow" you may never recognize them -- accidentally "follow" them again, now intermittently. And could this be harassing to others, following and unfollowing them repeatedly. Also of course when you block someone they cannot happen to follow you by their own wanderings.
b) What is some decent, yet cheap software for matching who is following versus who you are following, that lists WHO each of them are with the ability to either block or unfollow them individually?