There are some free ebooks available from Microsoft press, some of the ebooks include SQL Server 2012 Introduction and SQL Server 2008 R2 Introduction. I downloaded the SQL Server 2012 ebook which was around 10 MB pdf file. The content was good in the sense of providing what are the new features available in SQL Server 2012, the book covers from Database Administration to Reporting services. The book is divided into two main parts Database and Administration, the Second part being Business Intelligence. The material is extensive in the sense that the content is not merely a bullet list of issues. Below is the link provided, I would like to that the SQLServerCentral.com for providing the links.
Hope you guys enjoy the ebooks.