One of the things I've always liked about Baen Books (Even though their catalogue is exactly what I don't enjoy reading) is that, by giving books away for free, they actually experience greater sales for their authors.
How about that? Isn't that fascinating? So many books go out of print, never to be seen again (Unless Project Gutenberg or something like it steps in), but by keeping the older books 'alive', Baen Books is able to invigorate interest in the author's current work. Makes sense, and I wish more places would do something similar.
Faber Finds - which is more to my taste - recently launched with the explicit purpose of publishing old, out of print works. Unfortunately, the price is exorbitant, which kind of defeats the purpose.