Txtr is also a platform for sharing public domain books. I have just created an account and will upload a few books in ePub-format (look for mtravellerh).
The books can also be read online and on iPhone (txtr app available on iTunes app store). The ePubs on txtr are fully justified.
I like the site's very nice, sober style and the ergonomic simplicity. Lots of Gutenberg texts and I guess all of Munsey's books are already available via txtr interface.