I have an account for one of my projects that I use to announce new releases and updates. This happens once every few weeks, so I would pay for an option to stick my tweet at the top of my followers' feeds for, say, a week. If Twitter would then also allow people to unstick a tweet after reading it (or opt out of sticked tweets altogether), I think it'd be a great and welcome feature to have for everyone involved - TWTR gets paid, I get more eyes on my tweet and others won't miss my updates, which is what they followed me for to begin with.