Not anything like as creepy as some of the stuff here, but here goes: many years ago i worked at a petrol station about 5 mins from my house. My wife (then girlfriend) was at nursing school about a 2.5/3 hour drive away. She's coming down to see me. About an hour into her drive she notices a car behind her keeping speed with her pretty exactly. Doesn't think too much about it because, hey, it's the motorway, tons of people driving in the evening will just settle in behind someone doing a decent speed. Makes the drive a bit easier.
Coming into the town we lived in she notices this car had pulled off as well. Still nothing of of the ordinary, just a coincidence he's going there too. It's a decent-sized town so hardly a surprise, it's Friday and the town she studied in had a lot of people who worked there all week and lived elsewhere at the weekends.
Here's where it gets weird-the car makes all the same turns as her. We lived in a real maze of a residential area so he'd have to be going to somewhere really close. Close as in the same cul-de-sac with a small turn circle at the end. We knew our neighbours (or more accurately, knew their cars)-this wasn't one of them.
She calls me from her mobile (against the law but hey, can't blame her) and i answer even though I'm working, because the petrol station is just dead (had been all evening). She's pretty worked up by now and asks if she can come and see me. Of course, i say. She explains the situation as she turns around in the turning circle, the car still following her.
She stayed in the phone the whole way to the station and those 5 minutes felt like hours. By the time she arrives I'm absolutely pumped with adrenaline, half-hoping this creeper pulls in so I can fuck him up. I'm literally bouncing from side to side in rage. The moment she pulls in I'm out the front door to see her. I'm a fat shit now, but back then i worked out a lot and played American football, plus I'm a well-built guy so i was pretty intimidating (think the bouncer no-one fights). The guy drove past super slowly, staring right at me, never breaking eye contact even to look at the road ahead, then when he'd have had to bend his head right round he looked dead ahead accelerated away. Never saw him again but boy did I check the doors and windows twice every night for a long, long time.