I met my college friends in my freshman year dorm, another when I went overseas on a foreign study program, and another at a party.
I met a lot of my post-college friends at my first job out of college... and then a whole new tranche of friends when I worked at a non profit for a while. Since then, I've met most of my friends through parenting. Either parents of my kids' friends, or the playground or a block party. Also, some people on Hellobee.
So basically: I've met most of my friends through college, my first job, or through my kids. You?