That's a great question! Two of my favorites, by the same author, David D. Friedman, are available for free. Salamander, is listed on his website as his second novel, with a link to the entire novel online. The second one, Harald, is available from the Baen Free Library, which he also provides a link for. His website is
This leads me to the mother load... the Baen Free Library. Follow his link, this is a collection of free online books volunteered by writers under the umbrella of Baen Books. There's a lot of great books here. They do have an ulterior motive... if you like their books, maybe you'll buy some by the same writers. More power to them! Nearly all of their books have wound up on my Kindle. And yes... I've actually bought books by some of these authors if I liked them enough.
Try them out, hope you enjoy!