Board Thread:General Discussion/@comment-5677224-20140322120515/@comment-24532951-20140322122738

Here are some:

Stage : play.clubpenguin.com/?login=true&rm=340#/login/

VR Room : play.clubpenguin.com/?login=true&rm=213#/login/

Town : play.clubpenguin.com/?login=true&rm=100#/login/

Dojo : play.clubpenguin.com/?login=true&rm=320#/login/

Dock : play.clubpenguin.com/?login=true&rm=800#/login/

Pet Shop : play.clubpenguin.com/?login=true&rm=310#/login/

There's a lot more query strings, and you just need a room id to search more query strings.