Developer website: MaxUAE
Zodiac is the only free, open source MSX emulator for Mac OS X. It currently supports both disk images and MSX rom files. Zodiac uses the SDL library for cross platform compatibility and can be ported to almost any SDL supported platform in existence. It requires that you install the SDL libraries to work. MSX system ROMs also are available for download.
Version 0.8.2: Minor update, feature set remains the same
Mac OS X 10.0 or later, SDL libraries.