Free and Open Source Software

Don't have a lot of money to spend on software?  Open Source software is not just free in terms of price, but you have the freedom to do whatever you want with it.  The software below is usually available for both Mac and Windows.  If you don't have an operating system, you can even get that.

OpenOffice.org - Office Suite including Word Processing, Spreadsheet, Presentation, Database
Firefox - best web browser
GIMP - Can't afford Photoshop?  GIMP is free.
Inkscape - Vector Drawing
InfraRecorder - CD/DVD Burning
Pidgin - Instant messaging client allowing many accounts (Yahoo, MSN, AOL, etc)
Adium - Instant messaging client for Mac OS X
smplayer - media player which plays lots of different video and audio codecs
Celestia - Star mapping software and explore the galaxy
7zip - like winzip, but way better (and free of course)
Blender - Want to make your own 3D movie and become the next Pixar? (Warning: steep learning curve!)

Ubuntu - Free Operating System, only for the brave who are basically ready to abandon Microsoft Windows. 
 

Free Music

Support independent artists by enjoying (legitimately) {free, low-cost, and/or DRM-free} music licensed under the creative commons:

Jamendo - large community of independent music with over 32000 albums available
incompetech - royalty-free music
Magnatune - monthly subscription for DRM-free music and support artists directly.