I always try to 'ding' my bell a couple of times as I approach people on the bike as a warning and also yell 'passing' or similar as I pass. And I always say thank you as I pass regardless of whether they acknowledge me or not. It makes me feel right either way.
I was actually talking to someone at work today and said that I feel safer riding on the road than bike paths. For my 23km commute I could do 90% on bike paths, however I do the opposite and do 90% on roads. Admittidly I ride out of the city so basically against the traffic and also have on-road bike lanes, but the attitude of other users of the bike paths scars me. The number of people I see either riding too fast, without lights, without any care for others is incredible.
It's not just commuting either.As a family we often walk along Merri Creek to the Collingwood Childrens Farm on the weekend (with a pram) and the number of people that don't indicate either by bell or yelling that they are overtaking is incredible. I have now taken to yelling out to them as they pass as it makes me so angry.