Here are some good places to look for free eBooks that I've come across:
Start here -
https://www.mobileread.com/forums/showthread.php?t=3968
Long MobilRead thread about eBook sources
http://www.feedbooks.com/list/view/22
Creative Commons (free) Sci Fi eBooks
http://mashable.com/2007/11/12/publi...ebook-sources/
Public Domain eBooks
http://www.baen.com/library/
Baen's Free eBook Library
PCH