Ultima VI - The False Prophet

Nuvie - http://nuvie.sourceforge.net/
Open source project for the recreation of the Ultima 6 engine running on modern operating systems.

The Ultima VI Project - http://www.planetdungeonsiege.com/archon/
Remake using the 3D Dungeon Siege engine.

Things Your Mother Never Told You About Ultima 6 - http://lightning.prohosting.com/~jpmorris/ultima6.htm
Hints, unofficial documentation, add-ons, editing tools, tricks, and screenshots.

Ultima 6 Online - http://www.geocities.com/galleondragon/
Fan made multiplayer (MMORPG) version, featuring screen shots and a forum.

Ultima VI: The False Prophet - http://www.uo.com/archive/ultima6/index.html
Maps, hints, and music.