I found most of the information about TITAN on these pages:

• Bruno's Titan Home Page (Updated 10th Feb 2008)
  Extensive information on the board game from Avalon Hill, including errata, character count, General article index, strategy, tournament schedules and results.
  http://wolff.to/titan/ (new link!)
   
• David Ripton's Colossus Homepage
  Colossus is a great Java clone of TITAN
  http://colossus.sourceforge.net/
   
• Jerry's Titan page (Updated 10th Feb 2008)
  On Jerry' Titan page you find more information about Colossus.
  You can also download:
  - Original "LAW OF TITAN" (Rules) Archive in PDF format
  - "Badlands" - Battelands and Rules Archive
  http://www.coiinc.com/people/scug/ (outdated link!)
  http://www.milwaukeerumble.com/colossus/ (outdated link!)
   
• BoardGameGeek
  #1 site for board games and with a lots of additional stuff for titan
  https://boardgamegeek.com/boardgame/103/titan
    
• Wimeran's Homepage (Updated 10th Feb 2008)
  He is the developer of the Masterboard Manager Software
  http://home.nc.rr.com/wimeran/titan/ (outdated link?)
   
• Tod's Home Page (Checked 10th Feb 2008)
  This site shows the token bitmaps for each of the Units found in Titan.
  http://home1.gte.net/tsh/titan.htm
   
• Daniel Thibault's Homepage (Checked 10th Feb 2008)
  He is the creator of the TITAN Battleland Construction Kit, which you can also download on this site.
  http://www.angelfire.com/pq/Urhixidur/Titan/Battlelands.html
   
• Warhorse Simulations: Free Stuff (Checked 10th Feb 2008)
  6 Balrog counters, Ent description, TitanGM (.zip file) Fortran UNIX program for moderating PBEM Titan games.
  http://www.warhorsesim.com/free_stuff.html
   
• Temple of Titan (Updated 13/01/2002) (Checked 10th Feb 2008)
  Play advice, GIFs of master board, and battle lands.
  http://members.bellatlantic.net/~kinjo/titan/titan.html (outdated link?)
   
• Tor Gjerde's Titan Homepage (Checked 10th Feb 2008)
  More new Battlelands, interesting new Masterboard variants
  http://gjerde.nvg.org/Titan/ (outdated link?)
   

More webpages

• Another Titan fan homepage (french)
  http://manutitan.free.fr/