Web based

• del.icio.us - online taggable bookmarking service.
• audioscrobbler - audio recommender based on your listening behavior
• flickr - a digital photo sharing website, taggable.
• vimeo - a digital video sharing website, taggable.
• ourmedia.org - free webspace for cc licensed media
• the wayback machine - snapshots of websites as they were a couple of months / years ago.

Server

• jinzora - Jinzora enables you to stream your digital music and videos to any internet connected computer using a web browser.
• wordpress - best free software blogging system
• twiki - most powerfull and best wiki software system.

Desktop

• firefox - the BEST browser around. Infinitely extendible, see also my extensions page.
• soulseek - great software to download music albums (for linux there is nicotine).
• azureus - best bittorrent client around
• Video Lan Client - plays ALL video files, codecs included, possibility to stream.