A lot of places offer free data storage these days but I’m concerned about security. How safe it is to store something sensitive there? You may think that your address is not sensitive data but you’ll have to reconsider as soon as some crook uses it to open a new eBay account…
So my idea is create a public data safe where you have full control what someone else can see. For example your address: Instead of giving a online shop your address, you give them a random ID and you give access rights for the delivery service to resolve that ID. The shop doesn’t know where you live (and your address doesn’t go “somewhere” when the shop goes bankrupt) and you still get your goods.
Imagine you have an accident. You’re unconscious and are brought into a hospital. They need to run tests to figure out your blood group. If they have to give you medicine, then you’re better not allergic to it. And how about alerting your relatives? Here, a random ID which only registered health care services can decode would help: You could put your health data (allergies, medicine that works better on you than other, blood group, relatives to alert, important facts like whether you have a heart disease, etc) online without risking to find them on the loose.
How would it work? The service itself would only store data which you send encrypted. So the encryption would happen on your computer. Better get that anti-virus up to date, though. Health or delivery services would put their “public keys” online on this site, too, so you could encrypt the data in such a way that you and they can read it (basically, you make a copy and encrypt both). This way only certain people can read the data.
When data is uploaded, it gets tagged as “address”, “name”, “age”, “medical information”, etc. and each piece gets a unique, random ID (so you can’t tell from the ID who it belongs to). When another service should be allowed to see some of your data, you take their key to encrypt a copy for them and send them the ID.
If your address changes (because you move), you’d have to update it only in a single place.
Drop me a comment if you like to implement this idea.
Dark Views 
Great idea but how do we implement it?
The main issue is not the technical side; that’s relatively simple to solve (or rather all the issues have already been solved).
What’s more important: How do we pay the bills? The idea is lacking a business plan, something that will generate a revenue stream so investors are interested into throwing money out way.