Combase: Nova: Offers fan fiction, game information, and message boards.
Game Revolution: Some cheats for the version on the Playstation.
GameSpot: Offers review, downloads, screen shots, cheat codes, and strategy guide.
GameSpot review: Review by Ron Dulin, [7.2]. "Apart from new art and a handful of new combat options, this is exactly the same game as UFO Defense, only much more difficult."
GameWinners.com: Offers a cheat for the DOS/Windows version as well as links to strategy guides.
X-COM - Terror from the Deep: Has fan fiction and downloads.