I used Twitter quite a bit for work purposes (before I left CNET/CBS last year to found a recommendation startup) and might have paid for it then. But the valu

I used Twitter quite a bit for work purposes (before I left CNET/CBS last year to found a recommendation startup) and might have paid for it then. But the value for me was in interacting with a large number of people, and I suspect even charging a few dollars a year would lead to the vast majority of accounts disappearing, reducing the remaining users' incentive to pay, leading to more accounts disappearing, etc.