Shilka Publishing is giving away a free eBook every day up until Christmas. Check back in with them daily for your new free book.
From the announcement:
Christmas is a time of giving, so during the week between Christmas and New Year, Shilka Publishing shall be making one eBook free every day. Check the website or our Twitter feed each day to get that day’s discount code.
All eBooks are available in PDF (for printing or viewing on a computer), Mobi (for Kindle eReaders and apps), and ePub (for other eReaders and eReader apps).