Apple - What could I use to read epub books on OS X?

Calibre

ePubRead Firefox Addon

Crossplatform Sony book reader

Mac OS X Port of FBReader

Adobe Digital Editions

Stanza is a very good epub reader for OSX that is free.

Scarlett in the Mac App Store.

http://itunes.apple.com/us/app/scarlett/id457009670?mt=12