I have a bell on my commuter. People always seem to smile when I ding it to pass. It's worked well.
On my road bike, however, I don't have a bell. I call out "(however many bikes) on your left."
I wish it weren't frowned upon to have a bell on a road bike. Maybe I should get one that I can just slap on whenever we're doing a slower trail ride. The bell sounds friendly and is easy to hear. In fact, my DH has often commented that he wishes he had one. If he's riding in front of me on the path, and I'm on the commuter, he'll give a wave to me when he's ready to pass and I ring the bell for both of us.
I know I shouldn't care if hard core road riders would never put a bell on their bikes, but (sigh...) I do.
2007 Trek 5000
2009 Jamis Coda
1972 Schwinn Suburban
"I rejoice every time I see a woman ride by on a bike. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood."
Susan B. Anthony, 1896