This is one of those things you stumble upon when playing around on the computer late at night. It will let you communicate with someone over a network connection using netcat and espeak. What one person types at one end will be spoken at the other.
Server command (must be run first so the client can connect to it:
netcat -l -p <port> | espeak
Client command:
netcat <server address> <port> | espeak
Once the connection is made, just start typing. If you want to test this locally on a single computer, run the following commands in different terminals. Each will use a voice with a different pitch so you can differentiate between them.
Server:
netcat -l -p <port> | espeak -p 0
Client:
netcat localhost <port> | espeak -p 99