FBReader is an e-book reader for various platforms. Currently FBReader works on both Linux and Windows.
FBReader supports a number of format including: epub, fb2, chm etc. For more information on the supported format, read Electronic Book Formats (supported and unsupported). However, pdf is not fully supported except for text which is quite a waste.
It s definitely a very light and low resource footprint application. You may want to consider Evince for a Desktop Document Reader Gnome evine - Document Viewer
To install for fedora 12, just do a
# yum install fbreader
