DataMind is a website offering free tutorials for the R programming language and tools that let you develop your own tutorials based on R Markdown. I have not tested any of this, but it looks interesting.
Jonathan Cornelissen, Dieter De Mesmaeker, Martijn Theuwissen, Bram Jans, Albert Jorrisen. DatMind Beta. Excerpt: “Our mission is to empower everyone to become a data analytics expert for free! To achieve that, we are and will be working non-stop to deliver anyone, teacher and student, with the best learning experience for data science and statistics.” Available in html format.
You can find an earlier version of this page on my blog.