I've always wanted Person Address Codes in the US.

1. No more annoying and temporary change-of-address forms. We just moved, and our mail will be forwarded for 30 days. After that, well, I guess we better become friends with the people who live in our old apartment in case we forget to update an address.

2. Privacy! I can give out a way to mail me something without telling people where I physically live. This is not a big deal for me, but could be a big deal for 'famous' people and victims of domestic violence.