On a whim, I recently bid the whopping $11 in my wallet on a used guitar practice amp with microphone at a charity auction. No one else bid...

I have no intentions/illusions of playing my harp in a band (or in public, for that matter), but it's kinda fun to play around with the mic and amp for something different. I've found that it is actually helping with my breath control-- with amplification, you hear every bit of excess air. I knew that I was using too much wind for some notes, but I had no idea how much. It also makes it quite apparent when you don't quite hit a note cleanly... I don't know if I'm necessarily getting "better, but my playing has become much more disciplined since playing around with the amp. Thought a few others might find that useful...