EPUB QuickLook plugin helps Finder to display iBok epub book covers. Specifically, if an epub book has been imported into iTunes and you see its cover art in iTunes, the same cover image will show up in Finder. That way book files become much more interesting when viewed in cover flow or icon mode. Requires Mac OS X 10.6 or higher.
Download EPUB QuickLook plugin
The plugin takes advantage of the metadata information assigned by iTunes. Ideally Apple should have included such a plugin in iTunes from the beginning, (and they will probably do that). Meanwhile you can download and use this one.
The installer installs epub.qlgenerator into /Library/QuickLook.