-- Charge celebrities and companies for the capability of having huge numbers of followers. Remember Ashton Kutcher's race to be the first twitter user with 1 million followers? Yeah. Having that many followers is valuable to the person with the followers, and caused actual strain on twitter's infrastructure. Why didn't they charge money for that?
-- Charge third party developers for increased API capacity. It's obvious that this is a pain point. Why not just provide the option to pay to remove this pain point? Maybe they are planning to? who knows
-- Charge users for special account abilities- like, perhaps, many of the features offered by tweet deck.
And yet we have them pursuing this artificial advertising strategy. sigh.
I can only think that the strategy they are pursuing is that they see twitter as a passive medium for celebrities to transmit messages to their fans. Like it's a text based TV, that they can run ads next to. Perhaps they have the user demographics to back this up. Us weirdo geeks that use it as a a many-to-many communications medium are the vast minority.