Tony Hawk's Underground:Official site. Features information, game features, media, links, contests, and a soundtrack.
Alias Clan: Creates and trades parks. Information on how to join, roster, and news.
GameFAQs: Provides information, FAQs, guides, cheats, reviews, and a message board. (PlayStation 2)
IGN: Offers cheats, FAQs, walkthroughs, review, previews, features, movies, screen shots, and forum.
Open Site: Includes information and review summaries.