VLC, the open source, cross-platform media layer for Windows, OS X, and Linux, finally hit version 1.0. VLC 1.0 includes a number of new features including new HD video codecs, finer speed controls, instant pausing, frame-by-frame playback, and a ton of bug fixes and minor GUI enhancements.

The swiss-army knife of QuickTime components. Perian is a free, open source QuickTime component that adds native support for many popular video formats.

Powerful high-quality video converter, player, editor for MPEG, QuickTime, transport streams, iPod. And now it is a DivX editor and encoding machine, and even a stream and YouTube downloader. For Mac OS X and Windows

VLC media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, …) as well as DVDs, VCDs, and various streaming protocols. It can also be used as a server to stream in unicast or multicast in IPv4 or IPv6 on a high-bandwidth network. It doesn't need any external codec or program to work.