Ultima VI - The False Prophet

GameFAQs: Ultima VI
Walkthrough and message board.
http://www.gamefaqs.com/computer/doswin/game/562662.html

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

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

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

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

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