Felix Salmon: "If I was charged with maximizing paywall revenue, I’d start with a very low fee indeed — maybe just a buck or two a month, to attract as many subscribers as possible and to get them used to the idea of paying for content online. Once the subscriber base hit a critical mass, then I’d start raising the rate, as quietly as possible. ... It would take a few years, but the end result would be many more people paying for their online subcription than if you started off with a rate remotely comparable to the price of the print subscription."