You maybe aware of the 24days.in/umbraco site that Chriztian Steinmeier created? Well he's done it again in 2014 and all the articles are now available for download as an ePub

More about the project can be found at this url: http://24days.in/umbraco/about/

The ePub can be found here: http://24days.in/umbraco/2014/epub/