The Kinesis Advantage works fairly well for me on the Mac. You can change key layouts on the keyboard itself (as opposed to the OS) if something isn't to your liking.
There is one thing that I missed though: play, pause, ff, volume and brightness controls on the keyboard. I haven't worked out a solution for volume and brightness, but play, pause, and ff I do with keyboard shortcuts through Quicksilver.
Just wanted to clarify: it looks like you _can_ set different key bindings for screen brightness in the Mac's preferences. I can't find similar for volume controls though...
There is one thing that I missed though: play, pause, ff, volume and brightness controls on the keyboard. I haven't worked out a solution for volume and brightness, but play, pause, and ff I do with keyboard shortcuts through Quicksilver.