Authors do this themselves on Leanpub. But the thing is, readers of the in-progress book actually end up providing a lot of that in many cases, by providing fe

Authors do this themselves on Leanpub. But the thing is, readers of the in-progress book actually end up providing a lot of that in many cases, by providing feedback to the author via email, Disqus or Twitter. (Development and technical editors function as proxies for readers. We've found that readers also do a good job of that!) [Leanpub cofounder here]