The Microsoft Technet site has made available a bunch of e-books in epub, mobi and pdf formats

At this moment there are 11 books available, here is the list

ASP.NET
Deploying an ASP.NET Web Application to a Hosting Provider using Visual Studio
Getting Started with ASP.NET 4.5 Web Forms (Beta)
Intro to ASP.NET MVC 4 with Visual Studio (Beta)

Office
Configure Kerberos Authentication for SharePoint 2010 Products

SQL Server
Master Data Services Capacity Guidelines
Microsoft SQL Server AlwaysOn Solutions Guide for High Availability and Disaster Recovery
Microsoft SQL Server Analysis Services Multidimensional Performance and Operations Guide
QuickStart: Learn DAX Basics in 30 Minutes
SQL Server 2012 Transact-SQL DML Reference

Windows Azure
Windows Azure Prescriptive Guidance
Windows Azure Service Bus Reference

Some of these books are pretty short, the shortest one is 6 pages, there are also longer books, the longest one is 422 pages. This a good deal, now you can load these books on your mobile device and even if you don’t have connectivity, you will be able to pick up some new things that you will learn from these books

You can check out all these books here: http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx