the thing with friends is a bit like... some last and others don't. common interests can do a lot to keep people together, but the longest lasting friendships are based on a match in personalities.
i met lots of people in uni, had a good time with them and all. but only two of them are people i still like to know that i can call any time and still have something to talk about, even if we haven't met for years. i'd greet the others with a smile, but they all belong to a particular sphere that isn't really part of my everyday life.
at a forums, i've met lots of really nice people that i like a lot. i still only get closer to a very few of them.
one sign of a good friendship, that could last forever, is that you're able to enjoy each other's company in silence, just as well as you never really run out of topics to talk about. don't stop talking to people, you'll eventually find those precious few.
oh, and congrats on your tranniversary!