Norwegians make friends the same way porcupines mate: Carefully. In fact, they (the Norwegians, I mean) are so careful about it, I'm still not sure exactly how they do it.
That was the short answer to Victoria's bafflement at Norwegian behavior.
Victoria says: "[S]ome people are quite friendly and will smile or even chat a bit but I am still so surprised by the number of people who will either look right at you without cracking a smile or uttering a single word or will walk past you as if you don't exist."
I'm sorry to say, but that aloofness is quintessentially Norwegian (and shared with the Swedes). The "cold north" isn't just a comment on the weather.
Norwegians simply are not in the habit of nodding and smiling and saying hello to perfect strangers, and sometimes not even to anyone they've seen 518 times before. (If I want to shock someone I've passed in the neighborhood 518 times, all I have to do is greet them. They never see it coming.) It is the most frustrating thing about them for non-Norwegians - and even for some Norwegians - but, believe it or not, the country has actually warmed up a bit since Norwegians started traveling abroad more.
The one exception to this rule that has always existed, is on hiking trails. Norwegians greet complete strangers like old friends as long as they are encountering each other on some godforsaken mountain top. You're considered rude if you don't say "hello" as you pant up a rocky climb and pass someone on their way down. You're not expected to stop and chat, necessarily, unless the other party is already standing still, but you have to nod, smile, greet.
That said, people involved in a common experience will start talking to each other. Perhaps not as easily as in the US, and there are regional differences in Norway, too, but in general, they will talk. Norwegians are actually quite garrulous once they get going. A common experience can be fellow dog owners, or stuck waiting for a late bus, or sharing a taxi.
Because of this, Norwegians (mistakenly) think Americans are shallow because we talk about anything to anyone, and all it takes is a "Hi, how are you?". I always have to take a deep breath when I visit the States, to prepare myself for being constantly asked by someone and anyone how I am, and I just ducked in to buy more batteries and chewing gum. It is easy to react like a Norwegian and think, "None of your business!", but it does start conversation and I usually don't have to make much effort; the other person is very happy to chat. I have found that it is quite cheering.
Let me digress just a bit. Bill Bryson's "The Mother Tongue", made me realize a few things about my native country versus the one I currently live in. Bill explained how the pioneers in the US had to consider all strangers as friends, unless there was evidence to the contrary, because when you're alone in a strange country, allies are always needed. This has influenced American attitudes towards strangers and American speech, as exemplified in the Texan greeting, "Howdy, pardner". The Norwegians, on the other hand, come from the opposite experience: The typical Norwegian had little contact with strangers due to a lack of travel and a sparse population spread over an area the size of California. That, coupled with incidents over the years of other nations taking over the country, helps to breed a territorial and skeptical attitude. With the exception of lone mountain trails: Then they all become Texans.
From my own personal experience, I know that Americans and Norwegians alike can count the really, really good friends - the kind that you can call at 3 am when your cat or mother has died - on one hand. Neither are shallow when it comes to who you trust with your life and your weaknesses. But history has made the two people approach friendship differently: Americans, because of their past, use the word "friend" of someone they like as a promise to hang out together in order to solidify the friendship, letting it grow and prove the initial trust was not misplaced. In Norway, "friend" is an honor bestowed on you after already hanging out together over time and one day discovering there's deep trust and affection between you.
I'm not entirely sure how anyone decides when one slides over from acquaintance or "buddy" to "friend". I usually wait for the Norwegian to call me "friend" first, just to be sure.