It would be cool if I could always find where the most popular places people are going to are. I wish there was a technology that could anonymously track (via our cell phones) where people are and show it on a map. It could even be a smartphone application that we can download that displays where the popular venues are.
News sites like Hacker News feature stories that readers have given the most votes to. Similarly, it would be nice to have a system that tells us where the largest increases in foot traffic are. For example, we can discover that there is a sale at our local store today because the number of people who went in increased 110%.
This system can also help law enforcement. They can start figuring out where criminals are meeting. For example, if it is 3am in the morning and there is suddenly a spur of cell phone signals in a mall parking lot, the police station can send someone there to check it out.
Of course, many might believe this as a violation of privacy. However, something like this has already been done. I just Googled “cell phone density map” and this article about MIT researchers came up: http://www.physorg.com/news6483.html
Now, let’s just make a map that neatly only shows the density of cell phones in shops and other recreational activity areas.
Benefits
Restaurants: If I want a quiet place to eat and I check out the cell phone density map and it shows that the restaurant has tons of people in it, then I can just go somewhere else.
Theaters: It’s opening night of a movie and I want to find a theater with the shortest line. I can just simply check a cell phone density map.
Classroom: In college, I sometimes I forget if there is a quiz in a class or not. I can just check if there are a lot of cell phones in that classroom 5 minutes before class to determine if that class has something important going on that day.
Traffic: Instead of going to Google maps to see what the live traffic is like, I can just go to this one-app-includes-all cell phone density map.
Nanxi Liu 
Amazing! Very useful, especially since I was curious about the same while discussing with a friend of mine the other day. Thank you for sharing this.
Thanks! I’m glad you found it useful!
on the other hand you can check places, where there no people at all or almost no people at all… if you want to hide? or rob someone? but available only in shops and other recreational activity areas makes sense.
As lon as participation was opt in. I enjoy my privacy and I’m just not comfortable with any service tracking my every movement. I should have the right to share the info or not.
This would, like many information advances, provide some benefits. The many losses, however, to our already decreasing standards of privacy, for me, outweigh the benefits you describe.
Great idea. I don’t think it’s an invasion of privacy if it wouldn’t reveal the cell phone owner’s identity. My husband doesn’t like crowds so I know he’d be interested.
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