I have an Air Zound on my bike but would never use it on a ped, unless it were a matter of life or death. I save it for dogs (rarely) and crazy drivers (don't use it as often as I should!)

I was riding on a MUT yesterday and started getting close to a woman walking her dog. She had NO idea I was coming up behind her. She was on the left of the MUT, dog was on the right, sniffing the grass. They were meandering along slowly. I was ever-so-slightly annoyed initially, hoping she'd get over before I had to tell her I was there, but decided that being very nice was by far the best approach. So, as I got closer to her, I said in a friendly voice "Hello! Bike coming up behind." She looked, moved right, flashed a huge smile, and said "thanks for the warning!" in a friendly way. I passed, saying "Thanks! Have a great day!"; she replied "You too!" It ended on a very upbeat note that left me in good spirits. Sometimes, I just have to remember to slow down and take a different attitude towards the encounter. By handling it in a positive manner, sure, I lost some speed, but I also lost my annoyance and came out of it feeling all warm and fuzzy.

I also like to think that I left a positive "cyclist experience" on the woman, who had probably had some that were less so (haven't we all, as pedestrians?)

Totally agree on the iPod peds, though. Very frustrating! It's not even worth trying to be nice as they normally can't hear you anyway.