Things You Learn in Crowds
There are a couple techniques that help me get through crowds with a minimum of hassle, and both of them relate in an interesting way to iaido.
The first is this: when moving quickly through a very dense crowd, try not to lift your feet off the ground. If you do, there's a good chance you will step on somebody else's foot, and completely aside from the pain you inflict on them, it really throws you off balance. Instead, slide your foot across the floor. Just like in iai. Forget about all those things people say about why we slide our feet in iai: it's just more stable.
The second thing is this: when you're trying to move quickly through a medium density crowd, the kind where everybody seems to be going in a different, random direction, don't look at people's faces. If you do, you will almost certainly collide with somebody who is staring off in one direction while walking in the other. Or, you will make eye contact and then do that "Which way are you going?" dance where you both step left, then right, then left, then finally bump into each other. (This sounds like a good way to meet girls, but it really isn't.) Instead of looking at people's faces, look at their feet. Feet don't lie. If somebody is going to make a sudden turn, they will indicate it with a twist of the back foot. (Soccer goalies have known this for a long time: they watch the striker's "other" foot - not the one they kick with - and the direction it plants the instant before the kick is usually the direction the ball is headed.) Bearing this in mind, this may be why kendo is so stringently done with feet locked front-to-back - not only to reduce the chance of injuries to the achilles tendon, but possibly also to avoid telegraphing one's next movement. Maybe?
Oh yeah. The other thing I've learned from being in crowds: I don't like crowds.