I just made a small epub file containing a simple paragraph with multiple sizes to help me evaluate fonts:
http://www.chauveau-central.net/pub/font-test.epub
The zebra image between the text pages can be used to check the impact of 'ghosting'.
The sample text is in french but it can easily be changed by editing the file Page_1.htm file (if you don't already know, an epub is nothing else than a zip file)
The current text is supposed to contain some bold, italic and oblique samples but, as indicated in some previous posts, this is broken in 1.95 :-(