This is my first project, for school, and the forum helped me so much - even though I only fed on old threads - that I feel the need to give back. It's not a complex project but I was very happy with the result and couldn't find anything exactly like it!
    The project is a freeze effect that only activates when it detects a signal going over the determined threshold. Gated latch, maybe? Then the trigger signal stays feeding-back in the loop until another signal activates the detection gate which clears the previous.
    After that I added a hi-pass filter in case you want to clean the loop of it's low frequencies (0 - 1200Hz) and an oscillating pitch-shifter with a BPM rate (40 - 240BPM) plus an adjustable range for a random shifting frequency (0 - 5000Hz).
    I hope you like it and/or it's useful for someone.