IPartyThis is an old program that Intel worked on back in '95, gave up on and released it to the public. You'll have to change your name manually, but it works VERY well. The zip file includes both the server application and the client.
IParty.exe - client
IPartyD.exe - server
To change your name:
Edit the Client.ipl file (located in IParty/Sessions) and scroll down to the part where it says "< Your Name >" and change it to whatever you want. The <> aren't necessary, but the "" are. Then save the file and run IParty.exe. You can use any text editor to edit the file. I happen to use notepad since it works the best.
I've used it to communicate with

of my friends in the past. Even with some of the peeps here. (Shrike and Darkage are the first names that come to mind, but I'm sure there were others from here that I've talked to.)
To connect to a server using IParty.exe:
Run IParty.exe
Click File, select Open Location.
Enter in IP address and click OK.
Thats it.
To host your own IParty server:
Run IPartyD.exe
Thats it.
Very easy, no? Just be sure to unblock port 6004 since thats what it uses to communicate back and forth. You can change this port by editing the Iparty.ini file for the client, and IPartyD.ini for the server.