In one of my numerous subscriptions these days, I found one very interesting post with a collection of over 85 different free e-books for Microsoft technologies – from Windows development, to Sharepoint and SQL Server. Most of the book in the SQL Server 2012 section are really worth reading. The collection you can find here.
Some of the books are covering quite basic stuff, but hey – those are still good reads. All the SQL Server books are available in .PDF format as well as e-reader formats so you can direct use them for your Kindle for example. So enjoy reading :)