SMARTreporter - get notified if one of your hard drives is going to fail. Of course, even if it does, you’re fine, because you’re backing up every day, right?

MondoMouse - I’m putting this so close the top because I’m totally in love with it! Resize or move windows without clicking on a window handle. Totally crucial for smaller screens, especially.

Déjà Vu – If you’re not backing up every day, you will lose something precious at some time in your computing life. I may not even touch your computer if you don’t have an external backup. So, we can use Déjà Vu to schedule backups. Plug in your Firewire drive, and enjoy peace of mind. SuperDuper and ChronoSync are also fantastic. Slightly different tools for different situations. Time Machine is an amazing piece of software, but after almost a year with it, I still find it very hard to trust as one’s exclusive backup method. We almost always have at least a SuperDuper clone on a separate partition. (By the way, if you were wondering, Apple’s Backup is kind of terrible, but the next version of OS X —10.5 Leopard, due this Spring — will include a program called Time Machine that promises a great new era in backups.)

AppleScript and Automator – Yes, I know these are built-in, but the point is fantastic sites such as Doug’s AppleScripts for iTunes and automator.us and Automator World are just fantastic for boosting one’s efficiency.

LaunchBar – The future of search was in our hands well before Tiger was announced! I can’t wait to see how LB incorporates with Apple’s next-generation operating system.

Quicksilver – A lot like LaunchBar, but free and with all kinds of neat little plug-ins built in. Quicksilver can also replace Spark to launch apps with keyboard shortcuts. I prefer the LaunchBar/Spark/Synergy/PTHPasteboard setup, mostly because Quicksilver ran a little slow on my PowerBook. Now that I’ve added memory to my laptop, I might give QS another try.

Default Folder X – How to get to favorite and recent files instantaneously. Tried-and-true since OS 9. Fantastic in a production environment.

PTHPasteboard – This free multi-item clipboard dramatically reduces my having to switch between applications. Keyboard activated, of course, or what would be the point. (BTW, Quicksilver has this, and Spark, and Synergy, all built-in.)

Spark – Set up your own shortcut keys

Unsanity haxies – These folks have been the most consistently great developers for minor-but-major add-ons for OS X. Check out:

• WindowShade – Bring back that useful little OS 9 feature
• Menu Master – instantly assign a keyboard shortcut to any menu item

Peter Maurer – I don’t use these so much anymore, but Maurer’s stuff is genius, much like the Unsanity group. He does Butler, which is a lot like LaunchBar and QuickSilver, but you should also look at:

• TextExpander – Autocompletes text that you type frequently (the company SmileOnMyMac bought it from him recently)
• Witch – Enhances the Apple-Tab application switching to include all open windows

Salling Clicker – the best reason to buy a Bluetooth phone
So cool, and man I miss it from my Sony-Ericsson & Treo days, but it ain’t available for the iPhone. The developer comments here.

MailUnreadStatusBar – puts a count of unread e-mails in your menu bar
Or you could go for Inbox Zero.

Synergy – best-of-breed iTunes control

You Control – I gotta admit, for a one-stop package, it’s worth every cent.
Haven’t used it in a while. It seemed to take a lot of resources.

MenuCalendarClock – iCal integration in a highly configurable menu-bar clock. And now there’s a new, free menu bar widget called MagiCal that does much of the same thing.

Text Wielder – a collection that will show in the Services submenu of any Cocoa (OS X-native) application. Look for more Services, such as CalcService, on VersionTracker. (Note: The link to TextWielder will begin downloading the disk image.)
Services were a fine idea, but they just never seem to have made it.

SBook – convert text to an Address Book card
Definitely made moot by Leopard’s Data Detectors

Just good software:

VueScan – The best scanning software available, and compatible with just about any scanner you can plug into your Mac

GraphicConverter – a great “can opener” for hundreds of kinds of image files