The x264 QuickTime Codec is a QuickTime Image Compression Component which uses the free, open source x264 H.264/AVC encoder. It can produce H.264 encoded video faster than the Apple-provided H.264, with more configurable options and better quality.
Perian is a free plugin that enables QuickTime to play almost every popular video format.
QTCoffee is a set of command-line Mac OS X utilities for manipulating QuickTime movies and other QuickTime readable media.
ogg vorbis quicktime component, ogg-streaming works with quicktime-player, but not with itunes