Most useful stuff: OmniOutliner, Scrivener, OmniGraffle, OmniFocus, LaunchBar or Quicksilver, Path Finder, and VMware Fusion.
Also terrific, but less focused on pure productivity: Adium, Colloquy, Fission.
Great utilities for maintaining your system: AppCleaner, AppFresh, MainMenu, Service Scrubber, Name Mangler, OmniDiskSweeper, Winclone, Tunnelblick, Toast. Growl comes in handy, too.
You might also find Leap useful, depending on how you like to organize your data.
In terms of text editors, TextMate and BBEdit (TextWrangler is the free alternative) have their adherents. So does SubEthaEdit for collaborative work. Some people like MacVim. I personally use Emacs.app, easily built from the emacs source tree.
If you do any serious hacking, MacPorts is terrific.
LaunchBar or Quicksilver: tough call. I haven't seen any Quicksilver updates in about a year, since the original developer open-sourced it. Supposedly a rewrite is in the works. In the meanwhile, I switched to LaunchBar. It's a little more responsive and stable, although not quite as feature-rich or as good-looking.
Also terrific, but less focused on pure productivity: Adium, Colloquy, Fission.
Great utilities for maintaining your system: AppCleaner, AppFresh, MainMenu, Service Scrubber, Name Mangler, OmniDiskSweeper, Winclone, Tunnelblick, Toast. Growl comes in handy, too.
You might also find Leap useful, depending on how you like to organize your data.
In terms of text editors, TextMate and BBEdit (TextWrangler is the free alternative) have their adherents. So does SubEthaEdit for collaborative work. Some people like MacVim. I personally use Emacs.app, easily built from the emacs source tree.
If you do any serious hacking, MacPorts is terrific.
LaunchBar or Quicksilver: tough call. I haven't seen any Quicksilver updates in about a year, since the original developer open-sourced it. Supposedly a rewrite is in the works. In the meanwhile, I switched to LaunchBar. It's a little more responsive and stable, although not quite as feature-rich or as good-looking.