Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Keybase Chat - End-to-end encrypted chat built into Keybase
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Pithos - pithos is a daemon which provides an S3-compatible frontend for storing files in a Cassandra cluster.
Expensive Chat - Chatroom where you pay per letter
Pandora - Pandora Radio is a free (ad-supported) internet radio founded in 2000.