LeechCraft is a free open source cross-platform modular live environment.
It has modules for everything:

* Full-featured web-browser with support for all major web-standards.
* Advanced multiprotocol modular IM client currently supporting XMPP (Jabber),
IRC, WLM/MSN, MRIM and quite a few other protocols and with a bunch of
features from metacontacts and Off-The-Record support to audio calls.
* Collection-oriented media player with a lot of features from gapless
playback and transcoding for removable devices to social features like
recommended artists and nearby events.
* Efficient and fast BitTorrent client with full support for the BitTorrent
protocol and all its widespread extensions and magnet links.
* Modular document viewer supporting PDF, DjVu, PostScript, MOBI and other
formats.
* RSS feed reader supporting common feed formats with extensions like MediaRSS
or GeoRSS as well as with extensive support for Broadcatching and podcasts and
their automatic retrieval.
* User-space package manager with its own repository of plugins, themes, icons
and much more.
* A bunch of Desktop Environment-enabling modules from window manager
controller to power manager, taskbar, tray and a customizable panel.
* The "Summary" tab that displays all your downloads, updates and statuses.

WWW: http://leechcraft.org/