Another warm welcome, earbleedz! Cool name!
I've done the harmonica thing sometimes, with mixed results. There are floorboards that add a bit of bass drum feel, but I haven't tried them. I have known of acoustic guitarists who would trigger, via MIDI, some prerecorded things for adding, say, soft strings to that last chorus of a balad, or a somewhat muted bass/drums backup for something more energetic. It can work, but a lot depends on how it's recorded and used.
cotten