Make Icon can read PDF files and uses the first page to create the icon. On non PDF files, it tries to open the file as a picture using QuickTime and takes the main image inside the file. So it should work with all file types QuickTime can read. e.g. TIFF, JPEG, BMP, Photoshop, GIF, PNG, etc. The source code is included.
Mac OS X 10.2 or later