With Sparrow 1.2, the email client gains connections with Facebook (for displaying friend pictures and adding friends from within Sparrow), a unified Inbox, support for Gravatar, Subject-based threading, the option to create a new message by Control-clicking Sparrow’s Dock icon, and localizations in eight languages. A variety of bugs have been fixed as well. I still can’t consider Sparrow as a usable Gmail client due to its newest-first conversation sorting (so threads must be read from the bottom up) and extremely slow load performance for message bodies. A free Sparrow Lite works with only a single Gmail account. ($9.99 via the Mac App Store, free update, 11.9 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.