FBReader is the only e-book reader for Linux that I can use without problems. Ubuntu users can install the program via the Synaptic Package Manager without any difficulty. After the installation, you can start the program from Applications → Office → E-book Reader (in Gnome).
The program is designed for small-screen devices and you immediately feel this from the start. However, this is not a shortcoming but rather a very simple approach that lets you concentrate on your reading rather than trying to figure out the user interface. When you start FBReader, you will be greeted with “About FBReader" which gives you some brief information about the program. In this window, you learn that FBReader supports many e-book formats, fb2, html, chm, rtf, plucker and it also can read from compressed archives, zip, tar, gzip and bzip2.
To add e-books to your library, click the “Add File to Library" button, which is the leftmost button on the program interface. You will be greeted with a simple file manager, which lets you add your e-books to your library. Do not forget to add tags and other relevant information to your e-books, since your library can get cluttered up in a very short time otherwise. When you finish adding books to your library, you can just click on the book name to start reading your book. The program does not let you add bookmarks, but fortunately it remembers where you left off so you do not need to go back and forth the next time you open your book.