Several weeks ago, I ran across a small OS X tool called The Unarchiver—a free replacement for the built-in BOMArchiverHelper.app utility that Mac OS X uses to extract zip archives. The Unarchiver goes beyond BOMArchiveHelper, handling more file formats (including 7-zip and StuffIt), including better internationalization support, and having a more Finder-like interface (multiple simultaneous extractions are in a single window). I’ve been very happy with it. If you run OS X and deal with archives often, take a look.