I have found this new site named smashwords. They seem to have this nice collection of free ebooks. And they can allow you to export the ebook in pdf, epub and mobi. So that you can easily read in any platform of your choice. I have also noticed that in some cases the prices of books are also cheap. You can get the books for cost around 50 cents or so. So that can add up for such platform. If you like cheap books then this is the place worth checking out. Have you downloaded any books from Smashwords?