I’ve added a chat room on this site. It’s AJAX based, low bandwidth, not Java or Flash based. I think it should work through company firewalls via a browser. You’ll find it under the links heading on the right.
One of the reasons I’ve added it here for those times when your moving images over your cellphone connection from a laptop and need to communicate to someone in your office while doing so and you can’t talk on your cellphone, obviously since it’s busy transmitting. And hopefully it should even make it through your company firewall.
And if you want to just use it to chat amongst each other that’s fine too. Test it out, let me know how it works.