Surely somebody has thought of this idea and started to implement it, but if not, I expect to be paid retroactively in ten to fifteen years when this catches on, if only for convincing people that they need this feature. I haven't registered a patent, but the idea is simple.
GPS in your phone that is readable by the person on the other end. Obviously you don't want your phone to become a tracking device for everyone, so you can choose to turn it off, or you can program your phone so that it will be readable by your friends or family, or whichever people you decide to turn it on for, in the same way you program unique ringtones for each of them today. It would only be visible to that caller when you answer the phone, so if you didn't answer it, no one could track you but the NSA.
Why would a person want to do this? For one thing, it will cut down on your hollering in a fucking video rental joint, "Yeah, I'm calling from the video joint. No, Blockbuster. No, I hate Hollywood Video, they kicked me out after that fight I got in with the clerk. Right the Blockbuster near our place. No, not the one on Tappan, the one on State Street!"
How many times do you want to pay for that conversation? Have you noticed that you have that conversation right now several times a day? Wouldn't you rather say, "Look at your phone. That's where I am. Now what do you want?"
Or how about this one: "Yeah, I'm at my Ma's. No, honestly, I'm at my Ma's. What the hell you want, an affadavit? I'm at my Ma's!"
"I'm in line at the grocery store. No, Kroger's. This one's fancier than the other one. I know, has the health department even let that one reopen yet? Okay, what you want to do is take the Jackson Road exit off 94, hang a right. Then you can either turn into Westwood Plaza or you can go past it to the stoplight, hang another right...."
Wouldn't it be nice to cut all that shit out? Zap. No more lousy directions from well-intended friends. No more giving lousy directions even when you don't mean to direct them off the end of a pier.
"Steph, hey. You mind if I join you? Great, stay there, I'll be there in a couple minutes."
"Hey, Joe. Where you goin with that gun in your hand? Never mind, I was thinking of the old days when no one had GPS on their cell phones, or before everyone saw the benefits of leaving their GPS position visible to friends and relatives. I see that you are headed in the direction of your old lady's place. Let's get right down to the question of why you're doing that."
It would present a problem when spouses expect to be able to track each other via GPS phone 24/7, or bitch at each other when one turns it off, or parents tracking kids. They'll work it out or work around it. For example, I heard that some schools block websites where kids can instant message or chat or use forums to pass messages back and forth to each other during class. As a workaround, they find a site like BusinessWeek or maybe a blog with articles about macroeconomics in Micronesia, and they leave notes for each other in the comment sections of the articles. Be crafty. You'll figure a way to cheat if you really want to. Pay a taxi driver a few bucks to take your bugged phone on his rounds for a few hours, then you can go get your cheat on.
It will save you so much money by stopping those "here I am" conversations, you'll wonder why no one other than Rob thought of it earlier.