Would it be possible to create a command line tool for Mac OS X and Linux? If you use ANSI C/C++ for your current tools core functions you could use gcc which is avaiable free for both OS X and linux (Mac xcode uses gcc) to create a core function command line tool. I and Others could create a GUI application for our platform to give the command line tool a GUI. For example I could create one in REALbasic for Windows, Macintosh, Linux all at once.