my list of essential mac freeware

system tools:
• Growl (popup notifications from apps):
  • iChat plugin
• xMod (tweak hidden system prefs)
• Cameras (configure what actions MacOS should take for each camera device you plug in!)
• Warp (move between spaces with mouse)
• Google Notifier (Google mail and calendar alerts)
• DropCopy (local network file copy)
• AppCleaner (application remover)
• Grand Perspective (where *did* all my disk space go?)
• Disk Inventory X (where *did* all my disk space go, part the second, because I didn't download Grand Perspective)
• iStumbler (wireless discovery tool)
• iTerm (a nice terminal replacement)
• Name Mangler (bulk file renamer)
• iStat Menus (menubar replacement/extra utilities)

communication:
• Adium (multiple IM service client - similar to iChat)
• Colloquy (nice IRC client)

graphics:
• GIMP (graphics program a la Photoshop)

development:
• MacVim (port of the Vim editor)
• Komodo Edit (multi-language editor)

screensavers:
• Soundstream (uses the microphone as input)
• Desktoy (perpetual motion)
• Fenetres Volantes (flying windows)

toys:
• MacSaber (turn your mac laptop into a lightsaber)
• SeisMac (monitor seismic activity on your laptop)

multimedia:
• VLC (multi-format player)
• Handbrake (DVD to MPEG-4 converter)
• MactheRipper (another DVD extractor)
• Senuti (get files off your iPod)
• Soundflower (Inter-application Audio Routing Utility)

games:
• Quinn (Tetris)
• Einstien Logic Puzzle (runs on Leopard, despite what the site says)
• Stella (Atari 2600 VCS Emulator)
• VICE (Commodore 8-bit computer emulator)

non-mac specific:

web:
• Firefox
• Firefox Add-ons:
  • Answers (popup dictionary/etc lookup)
  • ColorZilla (color picker/tool)
  • DownThemAll (multiple embedded content downloader)
  • FaviconizeTab (collapse tab to just the icon)
  • Firebug (very useful web development tool)
  • Flashblock (blocks flash content until you click on it)
  • PicLens (amazing wall-of-pictures viewer)
  • Tab Mix Plus (tabs on steroids - highly recommended)
  • View Image (Filename) (appends the name of the image file in the context menu)
• Google Earth
• Transmission (light-weight, mulitplatform BitTorrent client)