BMW 2002, Dodge A100, etc
Bells will help keep pace in commuting situations, which is nice. I sometime whistle, but when I ride my commuter bike with the bell they hear me way sooner. Need to get one for my road and mountain bike too so I can whip out the ding as I pass.T
Finally, when you smoke your friend on the downhill, nothing adds the exclamation point like a polite ding as you pass.