There are two versions here, a Max patch and a stand-alone Mac OS X application. If you are on a Mac and you don't have Max, you can run the application. If you're on Windows and don't have Max, you can run the patch version, if you install the Max Runtime for Windows.
Download TheMill Patch for Max 4 - last update 12/23/07.
Download TheMill Patch for Max 5 - last update 4/22/08.
Download TheMill Application (Mac OS X) - last update 12/23/07.