I had an e-reader for Christmas and I've discovered lots of sites that offer (totally legal) free downloads of books that're in the public domain or being offered free by the publisher/author. I'm addicted. I've been grabbing books with both hands, making little squeaky noises of glee. I love old books, like 1920s, 30s, 40s books, and especially childrens books/detectives from that era, and though sadly some of my top authors (the ones whose books are incredibly collectible) aren't available, I've picked up many new to me titles by authors I love.

Some sites I've found useful are the various Gutenberg ones and these two:

http://girlebooks.com/

http://openlibrary.org/