• Adobe Acrobat Reader (Mac/Win)
  Used to view and print PDF files (Portable Document Format), a universal file format that preserves the fonts, formatting, colors, and graphics of the original document.
• Flash Player (Win - Internet Explorer)
  Flash Player (Win - Netscape)
  Flash Player (Mac - OSX)
  Flash Player (Mac - Power PC)
  Used to view multimedia buttons, interactive animations, flying logos, and graphics created in Macromedia Flash.
• QuickTime (Mac/Win)
  Apple's video technology allows you to play high-quality video directly on your computer.
• RealPlayer (Mac/Win)
  Used to play streaming audio and video on networks and the Internet.
• Shockwave Player (Win - Internet Explorer)
  Shockwave Player (Win - Netscape)
  Shockwave Player (Mac)
  Used to view dynamic and fully interactive animation, audio, and multimedia content created in both Macromedia Director and Flash (includes Flash Player).
• Windows Media Player (Win)
  Windows Media Player (Mac)
  Microsoft's audio and video player integrates other media features, such as a CD player and Internet radio.
  

Compression Utilities:

• StuffIt Expander (Mac/Win)
  Used to expand and decode compressed files.

• WinZip (Win)
  Used to unzip compressed software files.