Apple has released AirPort Utility 6.3.1 for Mac, which tackles a lone problem where some AirPort base stations failed to appear in AirPort Utility. It’s available via the Mac App Store, Software Update, and Apple’s support site. Additionally, version 1.3.1 of Airport Utility for iOS has also been released to tackle the same issue. (Free, 21.4 MB)
Mac OS X Zip Expanding Utility
Firefox (and possibly other applications) may ask you what you want to do with .zip archives that you download from the Internet. If you want to expand them with Mac OS X (rather than StuffIt Expander), you may be unsure of which application actually does the job. You're looking for Archive Utility (in Leopard and later) or BOMArchiveHelper (in Tiger). In either case, the application is stored in Hard Drive/System/Library/Core Services/. Don't move it from there, though, or you'll confuse matters.