This garden railroad modeler built a morse code signaling beacon for his layout driven by a Picaxe 08M. He shows you how to design it to either flash or sound out your desired messages. The builder also updated he article a few years back with a more hardware-friendly Microchip 16F684 PIC processor.
Morse Code Beacon
http://blog.makezine.com/archive/2008/07/model_railroad_morse_code.html