This idea of voluntary micropayments to writers has been around for a while and it’s never gained traction but people keep on trying:
For whatever reasons, this practice hasn’t really taken off, but startups are clambering into the space to make it happen. Flattr has been trying for a couple of years. So have other micropayments startups such as Kachingle and 25c, while Google has been experimenting with micropayments with its Wallet service. Dwolla is letting people pay each other over Twitter, and Vimeo recently started offering a tips jar for content creators.