TotalWar.com
Official site, including a clans list, strategies, and downloads.

The Org
Offers forums, screenshots, downloads, and links.

The Net
Unofficial Total War fan site offering downloads, discussion community, single and multiplayer information, and technical help.

Total Rome
Fan site includes news and history, downloads, screenshots, a forum, and tournaments.

Total War Center
Unofficial site offers forums, screenshots, reviews, cheats, guides, downloads and articles.