Beyond the Sword

GameSpot
News, previews, images, videos, links, and a forum.
http://www.gamespot.com/pc/strategy/civilizationivbeyondthesword/

GameSpy
Provides information, screenshots, and a preview.
http://pc.gamespy.com/pc/civilization-4-beyond-the-sword/

GameZone
Provides information, news, screenshots, and links.
http://pc.gamezone.com/gamesell/p32175.htm

IGN
Screenshots, previews, news, and a message board.
http://pc.ign.com/objects/896/896712.html

Wikipedia
Article describing features, new content, and new scenarios.
http://en.wikipedia.org/wiki/Civilization_IV:_Beyond_the_Sword

Eurogamer
Preview, by Richard Melville: "To conclude, this expansion is mind-boggling." <small>(May 25, 2007)</small>
http://www.eurogamer.net/article.php?article_id=76804