Moon Maiden made her one and only significant appearance in JLA Eighty Page Giant #3. In the story, it turns out that Moon Maiden is a forgotten casualty of a forgotten crisis, The Century War. She had gravity manipulation and "lunar madness" inducing powers, and was a long time member of the JLA before being retconned out of existence, and this tale dealt with her reintroduction to a JLA that had forgotten her. They seem to have forgotten her again, as I've never seen her since. I wonder if she's been re-retconned by Infinite Crisis?