Having recently gotten into digital reading I've gone around and looked into places to legitimately get free ebooks. Most will also distribute them as .pdf in addition to .epub files. Since many of these librarys cover the classics, there will be overlap between them.

• Project Gutenberg - The first and most famous one. Has mobile access.


• ManyBooks.net - huge ammount of great classics.


• Planet eBook - "high-quality — FREE — classic literature".


• E-Books Directory - Documents and lecture notes too, lots of newer stuff added daily.


• feedbooks - Older books now in the public domain.


• Texts @ The Internet Archive - "The Internet Archive Text Archive contains a wide range of fiction, popular books, children's books, historical texts and academic books."

I've also found places to pirate todays bestsellers, buy obviously I can't post that. However even on just one of these sites there is a staggering amount to look through. Certainly more than more than enough to occupy yourself with for quite a while.
Of course, if anyone knows of other such places, please do share.

Open Library is a good front-end to the archive.org and Project Gutenberg ebook collections.

ibiblio also hosts a few ebook websites, particularly for some specialist fields.

And, of course, there's Wikisource and Wikibooks.