Jason Emery's Phantom of the Opera page
This is impressive: eleven sections, including a BBS (with an awful lot on it), a FAQ, and a biography of Gaston Leroux, author of the original story.
Phantom of the Opera
Apart from a rather heavy Victorian graphics style, this site offers details on the London cast, awards, storyline, and the libretto.
The Phantom of the Opera Appreciation Society
Large and with pretty much the same info as most. Where it stands out is its Secrets page, with tidbits of information not generally known, and some interviews with four actors who have played the Phantom.
Nerissa Tong's Phantom
Page
Nerissa saw the show, read the novel, thought they were the best things
she'd ever seen/read, and set up the site. Nice design work, but there's
not much here that can't be found elsewhere.