Me too. It’s pretty standard around here to nod or smile a bit when passing strangers, and when walking in one’s neighborhood a greeting is the polite thing to do. People often do a little wave or nod while driving. Men probably do the chin-nod more often than women, but I think some sort of acknowledgment is normal. I’m female.
This is what I do, as well.
I never smile when making eye contact with strangers in Korea. People would think I’m nuts. I smile at little kids though.
I do smile at strangers when I’m in a Western country, just to be polite.
I think I’m going to move south, because that sounds real nice.
Female, living in a small town. I smile at everyone. Everyone smiles back and we often will exchange fast greetings before going about our business.
Of course, I’m one of those people who feels free to say complimentary things to a stranger about their outfit/bumper sticker/kids/pets to their face. I wasn’t nearly that brave when I lived in San Bernardino.
I (middle 40’s white chick) smile all the time here (in Japan). I don’t smile at random strangers unless they have a cute kid/dog/cat, but I smile at any and all service providers before speaking to them.
I take taxis a lot, and reflexively smile when I’ve flagged one down and the driver has indicated he’s slowing to pick me up. They usually smile right back.
I interpret in meetings, and will deliberately make eye contact with and smile at people I’m working with for the first time. It’s kind of hard to explain, but it helps me establish what I’m there to do, and assures them I’m impartial.
If I’m on the elevator, maybe. If I’m on the subway or street, usually no, unless there is something in the circumstances that would entail it, like if they asked me directions or if they had a cute dog/baby.
I live in New York City.
Sometimes
-
I smile at babies who look cranky, because giving them something else to focus on can sometimes stop fussy crying.
-
I smile at people who almost, but not quite, walk into me so they know there’s no hard feelings over them not paying as much attention as they ought to. They often smile back.
-
If someone does something amusing (in a way that suggests they want to be noticed) I’ll smile at that. This generally happens when people are in line.
-
And I smile at guys I catch staring at me, if they’re cute.
Otherwise, I don’t smile much at people I don’t know. And, true to the regional stereotype, most people around here don’t go out of their way to make eye contact with people they don’t need to speak to, either. It’s considered a bit eccentric to try to catch the eye of everyone you walk by, really.
I always assume when a woman returns my smile, she is just being polite. I’m gonna start assuming she thinks I’m cute.
It depends on the culture where you live, though. If everyone smiles at strangers, it might not mean anything, but otherwise, yeah, she probably thinks you’re cute.
It’s my understanding that various studies show that women are more prone to smiling at people than men are (but not more prone to smile than men when alone). IIRC, part of the advice that male-to-female transsexuals get when learning to fit in as a woman is to smile at people a lot.
Sometimes, mostly at little kids and their parents.
Not only do I smile, I sometimes say, ‘Hey.’
Yes, to both genders and all ages. Also, where I live, it’s common to wave at anyone driving by when you’re out in the yard.
I wanna think she’s being polite AND thinks I’m cute…
Wow, I’m the only curmudgeon here? I find that hard to believe. 
(I’m not really a curmudgeon, anyway. I’m just wary of strangers.)
I’m pretty sure smiling at people whilst covered in blood is still going to do the opposite of brightening people’s day.
I do smile at strangers, open to small talk too, but don’t complain in my ear lady.
I have been rebuffed, and ignored. :Shrugs:
Still, though I am one who does not take kindly to being told to smile, I do try to keep the corners of my mouth turned up. 
And my lesson to myself is, to be open to the smiles and contact of other like strangers in the world. They are few and far between out here, or so it seems…
When I moved down to NC from Chicago four years ago this was one of the things I had to get used to, and it is nice. Once I started talking with a young woman while we were waiting for the bus, and we just kept talking on the bus until we got to my stop. She was probably less than half my age, and I can’t imagine anything like that happening in Chicago.
And yes, I’ve now picked up the same “smile and nod to everyone” habit. The drawl is a little slower in coming, but I’ve found myself picking up other Southernisms.
I noticed that distinction with the Japanese students at my college. When I would smile at them, they always looked down like they were embarrassed, while, if anyone else didn’t return the smile, they would either not react at all, or look away.
As for the OP, I may smile and nod, or scowl and look up, depending on the person. My dad does this thing where, when he’s driving, he waves at everyone who passes him with just a finger. It’s funny to watch.
I generally find that the height of the smile is pretty indicative of whether the person is doing it to be polite, or whether they also smile at everyone. Length is a bigger indication of whether they want to talk.
(I’ve always been fascinated by body language)