http://p083.ezboard.com/bphantomphorum
Phantom of the Opera forum created when the biggest fan based forum disappeared a few years ago

http://www.phantomoftheopera.com/modules/newbb/index.php?
Replacement for the largest forum started by those who created the original

http://www.phansonline.net
Created after pfn became mfn, all kinds of Phantom costuming

http://www.musicalfans.net
Started life as phantomfans.net, all the old posts are still there. Much discussion on phantom costuming for stage and screen. As well as the other productions/books etc.

http://www.thephantomoftheopera.com/poto/phpBB2/
Message board of the official site.

http://www.forum.operaghost.pri.ee/index.php?s=25d0f9eb1294bb6b164bb8a63ee399da&act=idx
Le Forum, another forum started when there was a dearth of permanent forums.

http://movies.groups.yahoo.com/group/phantomcostumes/
Yahoo group for phantom costuming, movie focussed but some stage discussed

http://groups.yahoo.com/
Search for more phantom related yahoo groups.

http://www.livejournal.com/userinfo.bml?user=poto_costuming
Livejournal poto costuming community. You need to be a member to join, but you can still read if you are not

http://www.livejournal.com/interests.bml?int=phantom+of+the+opera
Search for all groups with phantom of the opera as an interest. Also search for phantom and different character names.

http://www.trulyvictorian.netfirms.com
Truly Victorian forums. Discussion group for the pattern line, several threads about phantom costume from stage and screen