So, how do you actually download these books?
It largely depends on what site you go to, and if you can’t find a book on one site, you can probably find it on another. For instance, ReadPrint.com, as well as The Literature Network (mostly major authors), and Librivox (audio books), Authorama (all in the public domain), and over a dozen other sites all have vast selections of free ebooks… More here.
Useful article. There are some seriously good books now available for free if you want to check them out.