The Scene Portal - The Demo Scene 

A demo is a program that displays a sound, music, and light show, usually in 3D. Demos are very fun to watch, because they seemingly do things that aren't possible on the machine they were programmed on. Essentially, demos "show off". They do so through either the computer's hardware abilities, the creative abilities of the demo group or through the programmer's abilities. Demos are an art form. They blend mathematics, programming skill, and creativity into something incredible to watch and listen to.
Text modified from it's original 'A Guide to the PC Demo Scene' form

What is the Demoscene?
History of the Demoscene

Demoscene.org - Daily demoscene news as well as downloads, reviews and links
GFX Zone - The biggest demoscene graphics gallery on the net
Orange Juice - The demoscene information center

  The Demo Scene - Scene.org

  The Demo Scene - General

  The Demo Scene - PC Groups (Listed Alphabetically)

  The Demo Scene - Disk Magazines

  The Demo Scene - Charts

  The Demo Scene - Alternative Scenes (No group submissions accepted)

  The Demo Scene - Country Specific Pages

  The Demo Scene - Parties