Unless it is explicitly stated by the author that you have the right to freely distribute their work, either in the book or on the download page, any other distribution is an infringement of copyright.
Most of us put our own links into freebies, so from that point of view the wider it spreads the better, however you would do best to check with the author if it is not explicitly stated. Even photocopying an article from a magazine is an infringement of copyright and the author would rightly expect a royalty for the use of their intellectual property.
Heres a freebie you can redistribute:
Create PDF ebooks with free software.