CoolReader will read from the external SD card as well as the internal storage. It also allows you to look for books in other places through its menus. On mine it lists all the booka on the SD card and indicates those I have read by giving file size - unread have no file size given. It will read a lot of formats, epub, html, rtf, txt and many others. Find it at http://sourceforge.net/projects/crengine/