Merlin Mann, editor of and primary contributor to 43 Folders.
Default Folder X ( )
You can tell Default Folder X is a classic because you start missing it the second you sit down at a Mac that doesn’t have it installed. It reduces the tedium of a handful of annoying dialog-box tasks, and it’s worth its price solely for the ability to set a per-program default location.
MailTags ( )
This Apple Mail add-on will make you scratch your head and ask why its features aren’t already available in OS X’s e-mail program. MailTags makes it a breeze to apply ad hoc tags, as well as—my favorite—generate iCal tasks and appointments that stay associated with the originating e-mail message.
SuperDuper ( )
This is the most brain-dead-easy way I know of to make a bit-for-bit bootable image of a Mac’s drive—a true lifesaver in waiting.
TextExpander ( )
This huge time-saver creates tiny text shortcuts for big blocks of text. It’s great for boilerplate responses, and it can also correct your most-common typos. It saves me a few thousand keystrokes a week.