I am an obsessive people watcher... I love watching social interactions, especially if there is someone else to discuss it with...
This is something seen often amongst the self-rightous, 'fit but my god don't you know it' types, who just seem men as people who oggle at them, and obviously all want them... its saddening.
Unfortunately the smiling and nodding in the street culture is also on the decline at a rapid pace... and it was only around in some cultures to begin with! Some places, for instance Poland when I visited, it was deemed rude to speak to someone you didn't know off the bat... or even to have any interation as you passed.
I may be wrong, but from conversations I have had with Danes, Swedes and some Finnish lads, Scandinavia seems to have a similar culture... where you have better luck meeting girls through freinds of freinds, and just approaching a girl in a bar is considered not normal...
I like to smile and acknowledge people in the street too, but quite often find it is not recipricated... maybe it is because I am also from a pretty rural town!