An echo system based on a tape delay configuration. Feed it with a short minimal line of music and let it evolve. It took me some time before I understood that this is a complete looping system, but that is exactly what it says: a tape delay effect. Great tool for endless minimal variations. It needs a small input to build up a complete sound. Bell sounds are wonderful signals to feed it.
Echomania has a nice interface. I expect it has so many possibilities I have yet to discover. The readme.txt is clear and a diagram is provided to explain the system.