One of my favorite places to find free ebooks and discounted ebooks is BookBub. This awesome site is where I discovered Kit Rocha's Beyond series, Kallypso Masters Rescue Me series and Bianca Sommerland's Dartmouth Cobras series. And right now, Kallypso has a free book (Masters At Arms) on BookBub as does Bianca (Game Misconduct).
You can find BookBub on Facebook too where they post updates everyday. If you love ebooks, this is a great resource. Now go check it out!