Open Source IRC
Internet Relay Chat is one of the most interactive and popular services on the Internet. IRC is the net’s equivalent of CB radio. But unlike CB, Internet Relay Chat lets people all over the world participate in real time conversations. IRC is where the Net comes alive Using an IRC client (program) you can exchange text messages interactively with other people all over the world. Some of the IRC software provides free download with source code to make it simpler and more popular among the users.
Useful Resources: Open Source Internet Relay Chat (IRC)