Internet Relay Chat (IRC)
The official IRC channel of Demigod can be found at #Demigod on irc.stardock.com
Impulse (stardock) features a built-in IRC client.
There's an IRC channel for the Demigod Wiki setup at irc.stardock.com, the name is #Wiki
To join an IRC channel type /join #channelname when connected to a server.
XChat2 (download) is a free IRC client for Windows.