Circa 1988 there was some kind of lottery pen pal system and, out of the blue, you would get a form to fill in which would ask you to state your interests and where you would like to have a pen pal from. I remember my slightly older friend getting her's first and being dead excited because i was going to ask for a boy and bag myself s French boyfriend when my turn came! i think i received 2 responses and the friendship fizzled out after just two letters. I'm sure this definitely happened, but cannot find any eveidence of why, when or how. My theory today was that it was some Government exercise to A) encourage international relations and B) an early ID system to keep tabs on the teenage population.
I also remember a magazine in the late 80s, which had a couple of pink pages in the middle with "personal ads" for its readers, again, in the vein of introducing penpals as well as offering a swapshop/fridays ads type service. Because it was based in the uk, you had a better chancce of finding a penpal closer to home. i thought this was a great idea, but unfortunately i think the magazine folded within a couple of issues.