I did scare the hell out of a jogger last winter though - dressed in black, listening to an iPod, at a well-lit crossroads on the path. I was approaching from behind, and was ringing my bell as he was in the middle of the path. I assumed that he might suddenly go left or right, so I slowed down as I could see that he wasn't hearing me. Well, he did suddenly veer right - but as he did he must have caught sight of my halogen lights out of the corner of his eye and he freaked out; stopped dead, mouth wide open and did a weird dance on the spot with his arms raised straight up and shaking about. I've since seen this dance referred to as 'the funky pedestrian'. I couldn't stop laughing for the next mile.
Tell you what - he was a brave man though; you wouldn't catch me running on a quiet off-road path in the dark at 6.00am without being able to hear what was going on around me. Prime mugger fodder !