You can turn your android device into your very own ereading device with the nook Android app.
You can shop for over two million books at Barnes & Noble, including instant access to hundreds of FREE NOOK Books, and sample any NOOK Book for FREE. Furthermore, you can view your own ePub files right from the app.
This app has many features to change the reading experience to fit your needs. You can change things such as the page color, margins, and line spacing.
I would definitely recommend this app to all the readers out there. You can get the app from the Android market here. The nook app is also available for the iPhone.