Before typing in the login info, type "USER" Admin Login:
User: cjohnson Password: tier3
User: *Whatever you want to put here* Password: Portal
Try typing "HELP" before logging in, you'll get a rather funny message. As Admin, type in "THECAKEISALIE" to get a secret message. As a normal user, type in "APPLY" to take a pretty hilarious survey.
Those are the things I've found from fiddling with the site a bit, go explore it and see what you can find! Enjoy! Just one more episode after this and the Portal LP is over. Thanks for watching everyone, hope you enjoyed it.