There is a new Android app that taps into Project Gutenberg, which is the largest archive of timeless classics and royalty free e-books. There are currently over 50,000 titles you can download to smartphone and tablet.
Gutenberg Books hit the Google Play Store a few months ago and has slowly been refined. There are animated page turns and lots of options to customize the reading experience.
There is a PRO version of this app, but instead of paying for it, all you need to do is leave a review. I think this is a sweet deal and draws attention to this great resource.
The Gutenberg Books app is not directly affiliated with Project Gutenberg, but if you read on your mobile device you will want to download it from Google Play or the Good e-Reader App Store.