The follow list of links was provided to us courtesy of new media artist Julie Freeman after her Unplugged talk, to encourage MzTEK and her crew to seek out and use open source software wherever possible.  Thanks Julie!!!

Learn more about Open Source and why you should use it, where you can.

Sound editing, recording, mixing, etc
Audacity
Ardour

Word processing/Spreadsheet/Basic Drawing/Presentation
OpenOffice
NeoOffice (OpenOffice port for OSX)

Desk top publishing/document layout for print
Scribus

Music player/audio manager
Songbird

Media player (plus encoder for formatting video and audio for streaming etc)
VLC

Visual programming language (similar to Max/MSP)
PD

Project management
OpenProj
ClockingIT

Photo and bitmap graphic manipulator
GIMP

Vector graphic drawing package for illustrations etc
Inkscape

3D graphic package
Blender

Simplified Java based programming language for artists
Processing

An OS Flash equivalent doesn’t exist yet but people are beavering away at it…
http://osflash.org/open_source_flash_projects

I also haven’t listed an OS equivalent of Final Cut Pro or Premier, but this sit has links – would be interested in any feedback if anyone has used any of these.
http://www.osalt.com/final-cut-pro

Mentioned by others:

Flash player (I’ve not checked this out)
Gnash

CanvasPaint – an online version of MS Paint

And of course – there are LOADS more…

Other useful links:

http://www.messageinabox.tacticaltech.org/
http://www.digitalartistshandbook.org/
http://socialsourcecommons.org/

Questions?  Comments?  Please comment if you have experience with the above software you would like to share, or futher suggestions.