Ultima IV: Quest of the Avatar  
   Origin's official site. World and dungeon maps, walkthough, documentation, and music files.
   http://www.uo.com/archive/ultima4/

Ultima Personality Test  
   Virtue based class-determination questions, game crib sheet, and character files.
   http://www.tk421.net/ultima/

Optima IV  
   A Virtual Basic clone of Ultima III and IV. With game design information, screenshots and download. Source and additional modules are available.
   http://www.wizardportal.com/optimaiv/

Ultima IV: The Dawn of Virtue  
   A fan remake project with 3D rendered isometric graphics.
   http://www.hut.fi/~jtpelto2/ultima4/

GameFAQs: Ultima IV  
   FAQs, walkthroughs and town script.
   http://www.gamefaqs.com/computer/doswin/game/11099.html

Ultima IV Website, by Samson Dragon  
   Provides walkthroughs, maps, and utilities.
   http://www.fortunecity.com/rivendell/dark/169/

Ultima IV Solution  
   Bare-bones walkthrough including all essential steps and items, by Stephen Lee.
   http://members.aol.com/UltimaFile/files/u4.txt

xu4 - Ultima IV Recreated  
   A remake of the classic computer game Ultima IV for modern operating systems.
   http://xu4.sourceforge.net/

Ultima IV: Gaining Virtue  
   List of actions that alter your virtue in the game.
   http://martin.brenner.de/ultima/virtuechanges.html