The New York Times has an article today about Broadway web sites. It not only discusses the rise in poularity of websites for each show, but the rise in Broadway fan sites.
Of particular note is Broadwayspace.com, which is kind of like MySpace but with a Broadway theme and catering to theatre fans. (From my brief visit there, high schoolish fans, but that may just be the snob in me).
One website not mentioned, but a must for musical theatre fans: BlueGobo. You’ll often find Broadway musical videos (usually of Tony Award show performances) there that you won’t find on YouTube.