I am not sure...
For all women that you don't know how old they are?
Madame is great when you're speaking French. :wink:
As for North American English, Ms, Miss, Mrs, work well. :D If you don't know if a woman is married or single, then you could use Ms (pronounced as Mi[z]) or you don't have to use a title at all. You could ask the person her name, of course. That would get rid of the problem. :D