Let me insert a stupid idea here that I just had: Would it be possible to use this with public keys from asymmetric encryption like PGP? The problem with PGP keyservers is that anybody can insert public entries that say "Email address X has key Y", even if you are not the owner of the given address. This is in fact a central problem in current public key encryption scenarios (authenticity). The most common solutions nowadays are certificates (requires a central authority) and web of trust (which has many problems on itself, practically and theoretically).

Now Bob could simply say "my user name is Bob" and insert the pair into the smartchain. Now if Alice wants to send bob an encrypted message, she can look up that pair given the identifier "Bob" and the current smartchain.

If that works, you can of course also use it to encrypt access to any kind of servers as an alternative to current SSL implementations, as well as pseudonymous p2p networks.