Otherwise, there's the "IRC" button in the navbar, but like Meishe91, you would be unable to change your nickname on there. You'll get banned from irc.chowned.org if you do so, since it does with many ppl for some reasons, and unfortunately, it's the only EFnet server that appears to work with PJIRC.
Another alternative is downloading a real IRC client, like mIRC, X-Chat. Some people also like Chatzilla too, altough it has memory leaks.
#omnimaga - calc games/programming, music, anime, starcraft, rom hacking and others
#ti - calc help and programming only
#tcpa - mostly off-topic and some rare calc talk
#cemetech - calc programming, unreal tournament, blockland, freebuild and other LEGO games.