I know this thread is a month and a half old, but here goes.
The GoodTech SoundsGood MP3 player does not currently have Mac software, so it's useless on a Mac (I have no idea why they did that).
However the MiniJam MP3 player works on a Mac.
I've not used it, so I don't know how good it sounds, etc, but it looks like the only Mac compatible one out there.
-THX
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Just because Windows users vastly outnumber Mac users, numbers alone do not denote a higher form of life. Cøckroaches outnumber humans many times over, and no one says a cøckroach is better than a human.