Corporate and university firewalls can be a particular PITA -- especially if you're a gamer. And while SSH tunneling (even over DNS)or VPN technologies are often preferred, it is quite possible to "bounce" your traffic off an Internet Redirection server. Like a fancy proxy, rinetd allows you to specify incoming and outgoing IP and port. It features basic client access rules based on IP and even supports logging. In my segment I demonstrate accepting traffic on port 80 and transmitting it to an IRC server on port 6667.

Granted this isn't going to fool your more complex firewalls that actually inspect packets -- but if you're just looking to get traffic through an open port I highly recommend giving rinetd a try.