People say IRC, MSN etc. is blocked, however, several companies I've used IRC and MSN as a resource for information (I have many people, "in the know" available on IRC and MSN) as well as a method of chatting/socialising. I've always done it with Putty's SSL proxy feature, with SSH running on 443, which is nearly impossible to block without killing all SSL sites (I say nearly, as some proxy software can deny the "CONNECT" command, however, it's rarely done).