A dutch forum has had the idea of making a few thousand small sticky-signs for on windows. A local sedansa-dealer kindly sponsored it. On the left side a red circle with in it a burning cigarette (with a bar or cross
through it); next to it, slightly overlapping, a green circle with an e-cig (penstyle for the difference) and 'e-smoking allowed' as text. At the bottom in small letters the forum-url, so anyone seeing it knows where to go for info.
Forum-members have them in their pocket when going about, and leave them behind wherever they find a place where the owner allows it or welcomes it.
I think a second dutch forum is starting on the same idea now too, so hopefully soon a lót of bars, shops and whatever will be having these signs on their doors or windows.
Idea for here perhaps too, something like this?