So, I'm not sure if this really fits since its not really an ebook publisher. But you might want to check out podiobooks.com. They have free audiobooks that you can play on your computer, mp3 player, kindle, ipad etcetera.
www.podiobooks.com
Of special note is Nathan Lowell's "Traders Tales" From "The Golden Age of the Solar Clipper". This six book series follows life in the space lanes for merchant traders. The writing is excellent. The books are narrated by the author, who has a very soothing reading voice.
I really enjoyed the series, although I didn't feel that the final ending was quite in the tradition of the bulk of the series. I still really enjoyed it all. The series is complete at podiobooks, and it is also being published (slowly) in written format at Amazon and other ebook retailers. Here is the podiobooks link for the free audiobooks:
http://www.podiobooks.com/podiobooks...+solar+clipper
And the Amazon listing for all of Nathan Lowell's printed works:
http://www.amazon.com/Nathan-Lowell/..._athr_dp_pel_1
None of the printed ebooks are on special at this time, but one or two have shown up free in the past.