How many times have you had to do the "sidewalk dance" where you try to shuffle out of the way of another person? Well there is a pretty simple solution.
Recently a friend of mine commented about something he read on reddit, people use gaze to figure out which way others are going. Now I'd been using this to avoid crowds, and even to indicate to my friends where to go next. However I realized that not many people know of this.
When a person walks around, they will usually glance in the direction they're going. This can be used to find out where others are going, and most of us do so subconsciously. However, the real utility lies in getting through a crowded area. Anytime there are people going in the opposite direction, you can determinately look in between people, or to thier side, and they'll make room for you.
Now one thing you might notice is that people who do a common courtesy (at least where I'm from), and glance into people's eyes, will be at a disadvantage. After all the other person now has no cues to tell where you'll be going.