Thankfully, r0ni works really hard at maintaining a version of MAME that runs natively on OS X (via Command Line, it has no windowed GUI).
It works great for most games, but you need to compile your own binary to get sample support for games like Zaxxon, and you can’t get access to the DIP switch settings for games, or advanced configurations. The free OpenEmu is great for running all sorts of emulators on your Mac with a beautiful frontend, and I heartily recommend it for consoles and computers, but its MAME support is classed as ‘experimental’ – indeed, you need to download a separate build to get MAME supported at all.
