My aunt recently purchased a book on how to learn Spanish that came with a bunch of downloadable audio files. However, the files were compressed in Zip archives that used a simple password from the book itself. She knew the password, but when she downloaded the files using Safari, Mac OS X's Archive Utility sprang into action, tried to expand the Zip archives, and promptly threw a completely meaningless error dialog.
Stumped by the error dialog, my aunt asked me what to do. For someone like me who has been using the Mac for years, the solution was obvious: use a free copy of Smith Micro's StuffIt Expander to expand the file, since StuffIt Expander is perfectly capable of expanding password-protected archives. When I thought about it from her point of view, however, I could see how the problem would seem daunting, especially since the Web page that provided the downloads hadn't offered any suggestions for utilities to use.
Curious if there were other programs that would meet my aunt's needs as well, I poked around a bit and came across The Unarchiver, another free program that claims to expand many more formats than Mac OS X's built-in Archive Utility. When I tested it with a password-protected Zip archive, it too performed admirably.
I'm sure there are other options out there too, but how many free utilities do you need for the same simple task? Perhaps Snow Leopard will feature a more-capable Archive Utility that can handle more formats and password-protected archives, putting this minor confusion to rest once and for all.