An interview with Marco Arment on GigaOM regarding finances and startups. Ryan Kim writes:

[Marco] started a $1 a month subscription plan in October that didn’t actually offer much in the way of extra features. It was more of a way to let users show their support for Instapaper. He said the response was overwhelmingly positive.

“That was a huge surprise to me how well it’s doing given there’s no real incentive to do it besides good will. But it ends up that good will is powerful,” Arment said. “It shows that people will pay for something they like because they want to ensure its future.”

“Let Users Thank You by Paying You”