Packt publishing give away ebooks, usually one per day. I regularly see Blender and or Cycles books being offered amongst ones covering game engines, Android, IOS, and programming (sometimes Python). E-books are offered in pdf, mobi, epub and other formats. Accompanying source code and or example files are zipped.
Give aways link: https://www.packtpub.com/packt/offers/free-learning
Requires sign up, but hasn’t asked for a verified email account yet (2016/12), so it’s pretty quick and painless.
Feel free to post up any offers that might be of interest to readers of blenderartists.
Todays free ebook is: Blender 3D by Example
Authors: Romain Caudron & Pierre-Armand Nicq
Published in 2015, using 2.74 going by some screenshots.
15MB pdf, 257MB zip of blends and textures.
It’s available for the next ~21 hours after which the next free ebook will be offered.
Is also available and has been for a while.