My favourite one is this:
I used to rent a big old house by myself. My friend Joe was between places and I let him store most of his stuff in my basement – but then he ended up getting a little studio space and most of his stuff remained in my basement. It wasn’t bothering me, so I didn’t put any pressure on him to find another place to store it. Later, my friend Myriah moved into the house, and she had a bunch of her stuff in storage at her parents’. Over a couple of months, there was some talk of getting Joe to move his stuff elsewhere, but I knew things were tight for him so I still didn’t put too much pressure on him. Things were being moved out by attrition, but it was going sloooooowly.
Meanwhile, my friend started taking some courses at Emily Carr. They randomly assign shared locker spaces because they don’t have enough lockers for their 1,500 students. She quickly became friends with the girl she shared a locker with, and eventually in the course of their conversation she was complaining bitterly that she had stuff she wanted to store and I was dragging my heels about getting my friend’s stuff out of the basement.
Names were mentioned, and eventually the locker girl realized that Myriah was staying at her boyfriend Joe’s friend Larry’s, and that half of the stuff stored there actually belonged to her.
She was much more assertive (and contrite, I guess,) than I was, and within a few days they came by with a truck and picked everything up.
There’s a useful coincidence – randomly griping about a personal situation to a random person who turns out to be intimately involved with it and can set things in motion to fix it. 
Another neat one: One time I was on the bus home from work, reading a book, which claimedd in a footnote that contemporaries of Plato’s were evidently cheesed at him for making sly references to the Eleusinian mysteries in his Symposium. This intrigued me, so I opened my notepad and wrote in it: Get Plato’s Symposium!
When I got home, a girl that I’d just started seeing and was absolutely nuts about was waiting for me on my porch. Before we even went inside, she opened her bag and said “Hey, I got something for you.” It was a very slim, very yellow little book, printed in the early sixties, which she’d picked up at a second-hand book store on the way over: Plato’s Symposium. She’d figured it would suit because she noted that my bookshelves contained a fair amount of philosophy (although none of it Greek.)
Given the extraordinary coincidence, (and the topic of the Symposium,) that struck me as so Significant at the time that, in hindsight, I can only be embarrassed. 
