Every install of Mac OS X comes with an app called ?BOMArchiveHelper.app? and you use it more than you think. You use BOMArchiveHelper.app to open compressed files. The Unarchiver replacement for BOMArchiveHelper. ?The Unarchiver is designed to handle many more formats than BOMArchiveHelper, and to better fit in with the design of the Finder. It can also handle filenames in foreign character sets, created with non-English versions of other operating systems. I personally find it useful for opening Japanese archives, but it should handle many other languages just as well.?
Once you have it in your Applications folder, just open double click on it and mark which type of files you'd like it to be in charge of opening.