GameFAQs: Ultima VI
Walkthrough and message board.
Nuvie
Open source project for the recreation of the Ultima 6 engine running on modern operating systems.
The Ultima VI Project
Remake using the 3D Dungeon Siege engine.
Things Your Mother Never Told You About Ultima 6
Hints, unofficial documentation, add-ons, editing tools, tricks, and screenshots.
Ultima 6 Online
Fan made multiplayer (MMORPG) version, featuring screen shots and a forum.