The Little MongoDB Book is a free book introducing MongoDB.
The book was written shortly after the creation of the MongoDB interactive tutorial. As such, the two can be seen as complementary.
The book is freely distributed under the Attribution-NonCommercial 3.0 Unported license.
The book is written in markdown and converted to PDF using PanDoc. A few LaTex specific commands have been placed in the markdown file to help with pdf-generation (namely for the title page and to create page breaks between chapters).