The book is available for first three chapters, and email registration is required to get it.

Thank you to @eschellman for the link to the archive source.

Updated the link for http://www.mmds.org/.
Removed An Introduction to Statistics with Python as it was not free. 
Removed The Architecture of Open Source Applications as it was a duplicate. 
Removed How to Write Parallel Programs as the domain is currently for sale. 
Removed CryptoParty handbook as it doesn't exist. 
Removed Network Science book as it 404s.

1200-page ebook is a deep dive for C# programmers who want to write applications using a single code base that targets the three most popular mobile platforms: iOS, Android, and Windows

Improved PHP Laravel books

Added Dayle Rees's *Laravel: Code Happy* book to the PHP list.

Eases the list lookup. Also added the author name to *Laravel: Code Bright* book.

The "Official Documentation (Offline Version)" Laravel book isn't free.