I agree about Twitter. I don’t understand how they intend to be profitable by making sure their users can’t use the website after 600 tweets read. This means less eyes for their advertisers, I would understand limiting within a short period of time like 600 in a half hour but 600 per day is pretty low considering how short tweets are. I can’t imagine they are going to be able to sell many advertisements without the users bothering to see them in case they run out of their daily limit.