Someone put up a few tracks from a band several years ago on some file sharing site and labelled them Hunky Dory outtakes. Up to this day I get questions about this! I remember vaguely the band was produced by Toni Visconti and their name started with an M.

Does someone remember the full story so I can simply link to this thread when the next person appears with the same question?

The band is called Marizane, and the track that usually pops up as being Bowie is called The Devil's Address (though I remember seeing some other Marizane tracks mentioned as being Bowie tracks).
There is some more info about the mix-up here and you can listen to some Marizane tracks here.