1d (One Id)

It actually surprised me that it took so long for a service like Google Voice to come along. No more arbitrary distinction between email, voicemail, sms and conversations: all use the same contact address (a 'universal' phone number). Sender and receiver decide independently how to send/receive the message.

I wanted this many years ago... (when ENUM came along and that didn't do the trick..). But today I realised you could even extend this idea to ordinary mail and travel directions as well. You could drop a paper letter in a mail box addressed to my universal contact point (say my email address) and it would get delivered to my current address (and maybe even scanned to my email address as well... Driving directions: maybe I'm not in town, maybe I moved and I didn't send you my new address,... TomTom can find me anyway.

You could also use this to enhance your privacy. Just create many pseudonyms, and use a fresh one each time you buy a book at Amazon.com. With this system, they no longer need to know your real address...