If you have two pickups, you can do the devil's horns thing with your index and pinky, although it makes me want to break people's er... pickups... when they do that. I saw a video recently where the guy pointed at his two pickups with his index and middle fingers and I thought he deserved an award of some sort. What is really confusing to me is how do you point at the pickups on a strat or any other 3 pickup guitar. Do you pretend you're Jerry Garcia and fold the middle finger under? Finally, if your guitar only has one pickup, and you have to point at it, the middle finger would be good if you didn't like it, and the index finger would be quite conventional, but what secret messages could you send by using your thumb? This is the sort of thing that keeps me awake these days.