oh i have loads of these!
We were in a random town in the middle of mexico and ran into a random person that we knew from the med school (in england).
My aunt and uncles friends from when they used to live in germany when i was younger turned out to be living in perth when we first arrived here. but ALSO someone my dad knows was saying about how they knew someone that was trying to decide between uni in wales or australia - and it was the same people - completely unrelated link there!
Before i was born my parents were trying to organise a boating holiday in france, but would rather go with people they knew. So they invited a couple who they were friends with and my aunt an uncle. however, my aunt and uncle didnt know this other couple, so in the end they decided against the plan in case everyone didnt get on, and ended up going on holiday just the two of them. BUT the other couple and my aunt an uncle also booked separate holidays, and so happened to book onto the same holiday (or the same place or something), met while they were there and got on like a house on fire! (As the saying goes)
Oooh another one. i was in my halls at uni when i first started there, in a random flat below me as i didnt have any flatmates yet. And in walks a pair of guys, as one of the guys was friends with one of the guys in the flat i was in. the other guy was a guy i knew from school and had no idea was going to be at uni, let alone in my halls!!! I ended up living with him in 2nd year actually, he was an awesome housemate!
thats all i can think of right now