I head about Craig Damrauer's New Math site from my friend in DC
When I was three years old, about the time my younger sister was born, I had an invisible friend named Jessica. We spent a lot of time playing together and I got very demanding when my family wouldn't take her seriously. My mom still remembers how I forced her to set a plate for Jessica when we all sat down for dinner.
I've moved four times since Jessica, very different times in my life, very different sets of visible, real-life friends. Right now, I'm lucky to have a lot of close friends in Santa Barbara. The really real kind of friends, who still like me even when I'm at my worst.
I always assumed friendships have an expiration date, that at some point you outgrow each other. Now I'm not so sure.