Making all users pay for each tweet might be a bad move, but perhaps something like, pay $X/month if you go over Y tweets would work better. I suspect that man

Making all users pay for each tweet might be a bad move, but perhaps something like, pay $X/month if you go over Y tweets would work better. I suspect that many of the heavy users of the service wouldn't object to that, since they already must be getting some sort of value from it to be using it heavily.