Being stupid is a wonderful thing: you discover new things every day.
I bought a Velleman USB Experiment board from Maplin as an exercise in learning how to solder.
One embarrassing turn led to another, and eventually I "discovered" that piezo buzzers generate current when you mash them.
That sparked the idea to use the piezo buzzers as a drum pad by converting the voltage into velocity sensitive MIDI notes.
Sadly, it had all been done before, many, many, many times.
But this is for all you Velleman owners out there.
See http://noshbar.xtreemhost.com or http://www.noshbar.co.cc if that ever works again.