The tkmacicon package renders platform-native icons on OS X as Tk images. The ::tkmacicon::retrieveicon command takes three arguments: a file path or file extension, width, and height. If a file path is specified, then the package will return the specific icon for that file as defined by the Mac OS, in the width and height specified in the arguments. If a file extension is specified, then the package will return the specific icon for that file type as defined by the Mac OS, in the width and height specified in the arguments. Specifying the file extension rather than the actual file can yield faster performance for large numbers of files.
Tkmacicon is developed by Kevin Walzer and is available at http://fossil.codebykevin.com