For translations for most of the duel songs except in the later sagas, visit duellists.tj .
This site has a lot of information, links, and images on the musical group Ban'yuu Inryoku, who sing most of the Shoujo Kakumei Utena songs (like Missing Link). Please note that this site is in Japanese, although it is not difficult to navigate if you are an English speaker.
This is another Ban'yuu Inryoku site, and possibly their home page. It is also entirely in Japanese. This site has images of almost all of the cast members as well as performance dates and locations. (This page tends to be down sometimes. If you are unable to view the it, please try the link again later.)
This site is in a combination of Japanese and English. It has the titles and (some) cover scans/images of practically every J. A. Seazer, Tenjousajiki, and Banyuu Inryoku CD.
If you like this site, you can vote for me here: AnimeTop Site List