When I'm running outside and I hear a bicycle bell, then I know that there's a rider behind me who wants to get by. But how do I pass by walkers easily without sounding obnoxious? Sometimes even saying (or gasping, in my case) "Good morning!" or "Coming up on your left!" doesn't get their attention.
The Runbell looks like a great solution. Kevin Nadolny and Tomoko Yano invented it to help them run through one of the largest cities in the world: Tokyo. It's a tiny bicycle bell that fits over two fingers. The user strums it with the thumb. It comes with silicone inserts so that it can be worn with or without gloves and still fit easily.