Multimedia
K-Lite Codec Pack
One of the best collection of codecs which enables playing all sort of movies
DivX Plus
A powerful player and converter packed with a bunch of basic tools for streaming and converting videos.
AVI to MP4 Converter
Simple tool that allows you to convert videos of the AVI format to the MP4 extension.
SRS Audio Sandbox
Nice application that acts as a virtual sound card and modifies the quality of the sound.