Autonomous Interactive Radio is a project to connect people. It's a radio station where you and your friends are the DJs, sharing music that you want to hear. By emailing an MP3 file to the radio station's gmail address, your song is added to a queue to be broadcast on an FM radio frequency.
You can build your own AIR broadcast station with an FM transmitter, the open source AIR software, a Raspberry Pi, a Gmail account, and an Internet connection. The parts of the station costs less than $200 with a 250 milliwatt FM transmitter. This setup will cover a few city blocks. An antenna for the transmitter will increase your range. Download the code here.