lxdream, the Sega Dreamcast emulator for Linux, was ported to x86-64 and Mac OS X.
From the official page:
It must be porting week - both the x86-64 and mac ports should (fingers crossed) work out of the box now. (Note that the mac port is intel only, and still requires X11+GTK 2.0 to build). Real native mac support will probably follow slowly as time permits - I’m getting something of a crash course in mac programming at the moment ^_^.
Changes
* Added x86-64 support to the translator
* Initial Mac OS X support (configuration and translator ABI changes)
* Fix buggy TRAPA instruction (translator only - fixes several homebrew games)
* Improve error handling of a few situations (can’t connect to display, etc)
* Esound is now optional (but without it you’re not getting any audio)
* Re-add the “Load Binary” menu entry that somehow got lost in the GUI revamp.