Command-Tab

The Unarchiver is a replacement for Apple’s relatively hidden “BOMArchiveHelper” application, which is responsible for the Zip, Tar, and gzip abilities built into the Finder. Not only does The Unarchiver come pre-loaded with much better archive icons, it handles Zip, Tar, gzip, bzip2, RAR (including multi-part RAR), 7-zip, StuffIt (but not SitX, sadly), and many other formats. Installation is as easy as dropping the program in /Applications, and then associating preferred formats to be opened with The Unarchiver. I find it’s a much better archive handler than Apple’s own, and the “brown box” icons help differentiate compressed files from regular documents.