here's a prototype spring reverb / delay unit i set up in my living room. it uses a 24' spring anchored with weights on either side. on one end, there are two piezo pickups, on the other, a speaker and an amp.
here's a picture of the pickup end:
i played (a slightly modified version of) an excerpt from the concerto in d minor by bach through it. click here to hear that. i eq'ed it and did some dynamics processing to sweeten it up.
there are also recordings of my own music being played through this thing. here is one:
still others will be up soon.