You may be acquainted with the project of the
Online Library of Liberty, a project from the
Liberty Fund which stores a great array of books about economics, philosophy, law studies and other social sciences.
While they stored their books in PDF format, they've realised lately that it was a good idea to convert them in ePub format as well, so they can be more easily accessible by eBook readers. They've managed to convert more than 700 books as of August 2010.
Here you have them for download individually.
However, if you feel interested in the whole collection, I've taken the liberty to compress the whole collection in a Zip file and store it in Ubuntu One. Here you have the link:
http://ubuntuone.com/p/Ecd/
It'd be great if you could provide feedback about their readability, either here or in their mail direction:
oll@libertyfund.org
Enjoy!