I signed up—Goodriter is free—primarily because there were some at-launch extras I wanted. Most were in PDF format, with a handful of ‘regular’ mobi/epub, and some on-line ‘courses’ too.
This turned out to be a good preview of the service itself. Their first dispatch came this week, and had more of those e-courses in it. It’s not just books; it’s other on-line content. That can be a bonus or not depending on your preferences. I am not a huge fan of the ‘online course’ format, personally, and if the emails don’t list enough ‘books’ then I will probably unsubscribe.
Still, it’s a freebie, so go ahead and give it a try if you’re interested.