CD Art Display - a desktop utility that shows information and CD art about the current music file playing
DivX - the codec needed to view most video files nowadays
MediaMonkey - a media player/organizer for audio files only
Mp3Tag - utility to rename and tag all your music files
VLC media player - media player good for playing video files, DVDs, and streaming video
Winamp - a media player/organizer for both audio files and video files

Daemon Tools - creates a virtual drive to load images of CD/DVD's
DVD Decrypter - removes encryption from a DVD and stores the files on your hard drive
DVD Shrink - compresses the video of a DVD to onto a single-layer DVD
Libra - an open-source movie collection database that imports DVD information from the web
Movie Collector - a movie collection database that imports DVD information from the web
Nero Burning ROM - CD/DVD burning utility
PowerDVD - software to watch DVD's on your computer

Mozilla Firefox - internet browser alternative to Internet Explorer

Firefox extensions - addons that allow different functionality. Here are a few popular extensions.

Adblock Plus - blocks advertisements and can also block flash and java
Adblock Filterset.G Updater - updates the definitions of Adblock Plus
Answers - desplays the definition of a word simply by clicking on the word
Better Gmail - allows you to customize Gmail with several options including functionality and appearance
Better Gmail 2 - same as Better Gmail but made for the new version of Gmail
Download Statusbar - manages and displays your downloads more efficiently
IE Tab - allows you to view a webpage with the Internet Explorer engine without having to open IE
Linkification - turns all text links into clickable links so you don't have to copy/paste
NoScript - disables Javascript on certain pages to prevent malicious code from running
Tab Mix Plus - allows you to customize how Firefox displays tabs and windows

Mozilla Thunderbird - email client alternative to Outlook
Foxit PDF Reader - a PDF reader alternative to Adobe Acrobat. Much, much faster
µTorrent - a BitTorrent client that is lite on resources, has an simple interface, and you can connect to via the web