The Titannica Wiki - Other fans of the Fighting Fantasy world of Titan have set up a mammoth database of information: The Titannica! What's particularly good about this is that it is a wiki-based system, so fan can liaise and add their own articles to the site.
Gamebooks.org - Gamebooks are a major interest for me--and have been so for many years. Demian Katz's Gamebooks.org is a well-designed, user-friendly site containing much information about gamebooks--far more than most people will ever want to know!! If you have even a passing interest in gamebooks, I also suggest that you join Demian's Yahoo Gamebooks Mailing List (information for how to join can be found on Demian's website).