Pazsaz Entertainment: X-Men Cartoon Series - - This site features a cast list, an episode guide with a synopsis for each show, and some background on the X-Men and the series.
Wikipedia: X-Men (animated series) - - You write the pages, as much or as little as you like, describing your favorite of all the episodes of X-Men: the Animated Series.
X-Men Animated Series - - Episode guides to both animated series, character biographies, the shows' comic book background, some movie information, links and interactive fun are all covered here.