Yemuzip was recommended at CMSExpo for zipping Joomla templates, modules, extensions, etc. because it doesn’t include some Mac junk that the Finder’s Compress command does. I haven’t had trouble with normal Mac zip files as long as I didn’t have any files with **s or other special characters in the file or folder names.
I downloaded this and tried it. It’s very easy to use and offers PC or Mac compatibility.