An interesting new project, Unglue.it encourages authors to liberate their books:
It works in three ways:
-Download links to free books
https://unglue.it/creativecommons/
-Download links to free books with optional donations to authors (to thank them for setting their books free)
https://unglue.it/campaigns/t4u
-Purchase links to books that the author has committed to make free when a certain target is met
https://unglue.it/campaigns/b2u
(via @paulfree14 )