[Update: since I posted this two days ago, I've gotten dozens of notes about systems in the UK, Australia and around the world that people say are "almost but not quite what you're describing." I also got a few notes pointing out that this was impossible and would never be done. Go figure.]
[New update! Matt points out that Apple has stolen this idea and applied for a patent.]
In 2000, I invented a gadget called RadaR. Fred Wilson told me that I was ahead of my time, and he was right.
RadaR.com was a hardware/internet hybrid that could eliminate boatloads of traffic (and frustration). The idea is this: traffic reports are useless, because they tell you about places where you don't want to go and because they don't help you make smart choices. Have you ever once been on the Father Baker Bridge? Me either. I don't care if it's closed.
When I go to the airport, I have a choice of three bridges. Which one should I take? If a smart friend was in a helicopter, she could call me and say, "don't take the Triboro (RFK)! Take the Whitestone..."
They never say that on the radio. "Hey Seth, don't go that way!"
Well, with GPS and a little spectrum, we could fix this problem in a clever way.
You get a box a little bigger than a pack of Altoids. There are four big red buttons on top and a serial number on the bottom. Type your serial number into radar.com then put in addresses for the four buttons (the airport, work, your grandma's house and Philadelphia, say). Then, whenever you get in the car, hit the button for where you want to go. The device speaks to you and tells you which route to take.
Here's the killer part: the way it knows which way to go is that everyone driving along with a RadaR device is consistently uploading two pieces of data: where they're going and how long it is taking to get there.
Since RadaR central has thousands of cars in every city, it knows which routes are fast and which ones are slow. Crunching some numbers, it realizes that the Whitestone is totally jammed and can send people over the Throgs instead.
I was going to seed the market by giving RadaR devices to taxi drivers, so we'd have plenty of data points from the beginning.
The challenge is that getting this much hardware to so many people is expensive. Not to mention the bandwidth.
You probably already guessed the punchline: Do it with an iPhone.
Have the iPhone use the gps data... upload where I was a minute ago and where I am now. Figure out my speed and route. Use the data to tell other RadaR users which route is best. It's worth $20 a month if you live in a place with traffic jams. It's a natural monopoly--once someone figures it out, why wouldn't everyone want to use the market leader?
I minimize the difficulty of technology implementation (and I'm usually right). So don't tell me why it's impossible to do this, just build it and I'll buy one. If you build it, let me know.
BONUS! Here's an easier one that you could probably sell as well. I type in a phone number and enter a time. Record a message and press go. I can cue up a bunch of messages that are based on time. I can have groups get the message I record, at the time I want them to get it. I can make announcements... For example, if the sign in at the gym starts at 6 am, I can set my phone and it will call ahead and sign me in. Or you could ping your exec team every morning at 8 on their way into work...