Here is a list of FREE books, eBooks and PDF's for all religious books, scripture, atheist and agnostic books. It's a work in progress but these are links that I've had time to check or have used in the past. Either send for or download. Some of these links may become useless in time so I'll try to keep it as functional as possible. Also if you have any free book links you want to add just drop it in the comments and I'll add it to the list.
Note: Some free books may require you to sign up to a mailing list or ask for a donation. I have tried to limit the use of these in this list however they are included.
Free Books eBooks and PDF
http://www.biblestudytools.com/cjb/ EBOOK/ ONLINE BOOK
Sri Guru Granth Sahib http://karandeep.tripod.com/baisakhi.htm
The Book of Mormon
Fantastic eBOOK resource listed here: http://hinduebooks.blogspot.co.uk/p/complete-index-of-free-ebooks.html