ABC: Mackenzie Watch
Official network site. Features show blog, character bios, episode recaps, video clips, and photo gallery.
http://www.mackenziewatch.com/

Commander in Chief TV
Show commentary.
http://www.commanderinchieftv.com/

IMDb: Commander in Chief
Cast bios, crew info, user comments, quotes, trivia, goofs, and production information.
http://www.imdb.com/title/tt0429455/

Wikipedia: Commander in Chief
Show summary, character bios, episode recaps, and trivia.
http://en.wikipedia.org/wiki/Commander_in_Chief_(television)

Yahoo! Groups: Commander in Chief
Show, episode and cast discussion. [Yahoo! registration required.]
http://tv.groups.yahoo.com/group/Commander-in-Chief/