That is, make it free for every user until that user reaches a certain level of influence. That way, you can grow without charging anything and then charge those who a) value it the most and b) have the money & reason to pay to sustain their influence.
Why can't Twitter create a pricing model for everyone with over 1m followers?
Why can't Facebook keep its service free for consumers but charge organizations?
The massive power of huge social followings (organic reach--without ads) is worth so much but valued at ZERO by social networks. I think it's a huge missed opportunity that is resulting in diminished value for everyone.