FWIW, I've gotten more positive feedback about the length of these than anything else. It isn't "thanks for making it free", or "thanks for making it good". It's always "thanks for making it short!" :)
Karl, since this is already written in Markdown, have you thought about putting it on Leanpub? Our books are in Markdown, and we generate PDF, EPUB and MOBI. We support variable price and a minimum price of $0 if you want, so readers can pay whatever they want as long as it's your minimum price. Royalties are 90% - 50 cents per copy. Finally, readers get automatic updates if you post new versions etc.
