I was reading a guide a few months ago about methods to use that will increase your twitter following and make the followers you do have pay more attention to your tweets.  There are all kinds of tools available to help you build a following, but if they don’t pay attention to your tweets, if you are trying to market something you are basically wasting your time.  I have found a site that offers twitter flash games that I share with my followers.  I have noticed an increase in my following and have less people unfollowing me.  This strategy is working out well for me.