- VLC Media Player: a "highly portable multimedia player and multimedia framework capable of reading most audio and video formats (MPEG-2, MPEG-4, H.264, DivX, MPEG-1, mp3, ogg, aac ...) as well as DVDs, Audio CDs VCDs, and various streaming protocols." And, though I haven't tested it extensively, VLC seems to be able to play DVDs from any region.
- Handbrake: maybe my favorite freeware ever. Great for ripping your DVDs for playback on your iPod, PS3, or home theater computer. (Handbrake requires VLC to rip some commercially-produced DVDs.)
- Perian: enables the awesome QuickTime player to read just about any video format (including the popular DivX and 3ivx formats).
- Silverlight: why would you want to install a Microsoft (!) product on your Mac? Because you need Silverlight to take advantage of Netflix's groovy "Watch Instantly" video-streaming feature.
- Flip 4 Mac: Speaking of Microsoft, if you come across any pesky Windows Media video files you need to watch with your QuickTime player, Flip 4 Mac makes it possible.
- Firefox and FireFTP: Apple's Safari is a fine browser, but it's not as customizable as Firefox. And my favorite Firefox plug-in is FireFTP, a clean and simple FTP client.
- Celtx: We no-budget filmmakers need to save money any way we can. Thank goodness for Celtx. It's a solid screenwriting app, and it's free. Which is to say, it's much more affordable than Final Draft.
If there are any cool free Mac apps I didn't mention, leave a comment and let me know about 'em.
One tech note: if you have a newer Mac and want to install the 64-bit version of Handbrake, you'll need a 64-bit version of VLC, available at: http://download.videolan.org/pub/videolan/vlc/1.0.2/macosx/vlc-1.0.2-intel64.dmg