This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
You should be aware that many sites that offer books for download are actually pirating copyrighted works. I assume you do not work for free, so you should give authors their due and purchase books that you use. That said, there are several works available under very generous licenses which allow you to download a copy. One such work is How to Think Like A Computer Scientist.