Just a thought... Apple should consider developing Quicktime and iTunes to accept mod files... Would this development be impossible or just a waste of time?
Apple?? Haha... No way, but it would be actually possible to write a Quicktime Plugin which accepts modules.
Btw. PlayerPRO went open source on sourceforge quite some time ago, but actually nobody seems to care about it.
It would be possible to write a piano roll pattern editor for MilkyTracker though.
Re: trackers, your best bet would probably be to set up some sort of dual-boot system, 'cos as far as I know, there's very little development happening for Mac, but lots for Linux and Windows.
I'm not sure whether you are referring to Trackers or just software development in general but there is a lot of development going on for OSX and since OSX is fully POSIX and UNIX compliant you can easily make any linux application run on OSX too without any porting effort and people are doing this quite frequently:
http://www.macports.org/http://www.finkproject.org/In addition there is a lot of OSX professional applications that is neither available for windows nor linux (especially for music/audio/video production).