When I was working on plans for the original PICAXE based train controller (see: http://www.trainelectronics.com/PicaxeSpeedController/article ) I brainstormed a bit about other things that could be done once you have an easy to use & reliable circuit for controlling trains.
I considered a number of things but the most interesting modification was to add a memory chip to the circuit so that I could use it to record a train-running session and then play it back over and over. The modifications to the original circuit that are shown here do exactly that: turn the device into a record / playback unit that does something that is rather unique in model railroading.
You can run the train in a complex pattern composed of forward movements, backwards movements, stops, slow speed running, higher speed running, etc and have it all recorded so that it can be played back again and again. Ten or more minutes of running can be recorded and stored indefinitely for playback.