Collaboration software to share files securely with your own network (friends, family, business network…). Includes secure instant messaging and secure screen sharing. Runs on Windows 2000 and XP, Mac OS X “Panther”, Linux, and FreeBSD.
http://www.shinkuro.com/products.php

Binary distribution of MPlayer (The Movie Player for Linux). Comes with native GUI in MacOSX. After installation you can simply play almost all 3ivx, DivX 3,4,5 and other codecs files in the window or fullscreen mode. Rendering of very nice antialiased text-based subtitles is also supported.
http://mplayerosx.sourceforge.net

Free web photo album software and image gallery software. This gallery software makes web albums of your digital images. JAlbum aims to be the easiest to use and most powerful tool in this category - and free! Runs on Windows, Mac OS X, Linux and others and speaks 18 languages.
http://jalbum.net

Cross-platform media player and streaming server, VLC (initially VideoLAN Client) 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.
Thanks Jul
http://videolan.org/vlc

Knoppix is a linux distribution that runs from a bootable cd. Try the penguin os without the hassle.
http://www.knoppix.org