Other then medical purposes, what other use is there for this technology?
There. You've just listed the most important aspect of this technology.
Also, it's not hard to imagine possible uses for this stuff, and uses for technology that can be developed with this breakthrough.
Phones do the same thing without implanting technology under your skin. And it's easier to show stuff on it to someone else, or lend it to someone.
True. But it's also possible to have it stolen. It's possible to have someone break the code on it.
Also, there's stuff that phones can't do. Can they monitor your heart rate? Your blood composition? Brain activity? Lymphatic system? Can a phone instantly show any health problems you may have? Can you go to a doctor with a pain in your chest, and have your phone explain the problem to him? Can your phone display to you a possible remedy? Can a phone monitor your blood-alcohol level, and tell you when it's unsafe to drive? No?
This thing can.
Now, let's take another possible aplication of this tech. Let's say you shove a wireless internet connection into it. You now have full access to the world's greatest repository of knowledge, wherever you go.
Sure, a phone could do that to. But you don't have to worry about losing it. You don't have to worry about it getting stolen. You don't have to worry about recharging it. You don't have to worry about paying for a new battery if the old one breaks. Everywhere you go, this thing will always be with you, and you don't have to worry about powering or maintaining it.
Now, let's connect it to that electronic contact-lens I posted a while ago. You now have full visual display for whatever your checking out. And that's a
lot different than looking at a screen on a phone. Now, the arm-thing can display warnings, advice, and all sorts of stuff directly to your brain, with no need to worry about you not noticing it.
Now, let's connect both these things to one of those Bluetooth headsets, or maybe something even more advanced and inconspicous than that (some sort of implant in the inner ear, perhaps?). You now have full audio capability, and full privacy for it. You can set it for just the right level of volume so that you and you alone can hear the conversation. You now have full audio/visual sensation with this thing, and the ability to access any information wherever you go.
What other advances could enhance this? Well, how about a sub-vocalising device? This would allow you to talk to whoever's one the other end of the phone, without it appearing that your talking at all. This thing alone would be invaluable in security and bodyguard agencies. In civillian aplications, it means you can have phone conversations without anyone even realising it. No more being interupted by someone's phone ringing in the movies; you won't even notice that everyone around you is talking to someone else. And there's no fear of being overheard. Perfect privacy.
Also, if we could get the device to recognise voice commands, that opens up a whole new bunch of possibilities. You could simply say (or rather, not say) "Go to Wikipedia. Search for Operation Overlord." and you get full visual and audio input about what you're searching for. This is, in effect, the next best thing to a full neural link-up.
Now, suppose we find a way to stimulate the nervous system with similar technology. You now have full tactile awareness. Imagine the possibilities of that!
You've just made computers a thing of the past. You don't even need a keyboard; the thing in your arm can act as a keyboard.