[stcredzero]

> You can't possibly trust any company with this kind of service.

That's a good point. However, the Swiss made a lot of money offering comparable services for many years. (Numbered bank accounts.) Also, there's a big difference between simply building such a service and having such a service that is well tested and reliably and securely hosted. It's also a relatively simple matter to test such a service with a small amount of money.

Such services seem highly valuable, but may require practical homomorphic encryption/computation schemes to be themselves practical.