FLDIGI is a fantastic digital method if you just want to broadcast a message to a lot of people without concern for a response or receipt confirmation. Setup can be as simple as a cell phone held up to an HT to a computer plugged into the digital port of a base station radio.

Here are some links to help you get started:

There is a “Digital Net” every Monday night at 8 PM, on the Columbia Tower repeater, 444.550 MHz, positive offset, tone is 141.3 Hertz.