The Sullivan Society - the website for The Sir Arthur Sullivan Society
The Gilbert Society - the website for The W.S. Gilbert Society
The Gilbert and Sullivan Archive was established in September 1993. It includes a variety of G&S related items, including clip art, librettos, plot summaries, pictures of the original G&S stars, song scores, midi and mpeg audio files, and newsletter articles. New items are added regularly.
A Gilbert and Sullivan Discography - Marc Shepherd's excellent discography includes details of recordings of G&S, including 78s, vinyl records, CDs and videos.
Gilbert and Sullivan Festivals - the home site for the International G&S Festival
Grim's Dyke Hotel - the website for Grim's Dyke Hotel, former home of W.S. Gilbert
British Newspaper Archive - has a good search function and contains lots of information about G&S, the operas, performers etc