http://www.phidot.org/software/mark/rmark/linux/
Please read the details carefully. The version of the MARK executable (32-bit only for the moment) was compiled to be as 'platform neutral' as possible, but that is not always easy to fully accomplish. In particular, if you're running a machine with a non-Intel chip (is that still possible for Macs?), and have problems, (i) don't be surprised, and (ii) let us know.
Reminder that MacMARK is 'used by you, and supported by you'. If it works for you -- great, awesome, verging on totally rad. If it doesn't, you're on your own.
Further, if you can't get it to play nice with RMark, then post a query in the RMark subforum (i.e., its all Jeff's fault
