If there was a peer-to-peer, encrypted instant messaging network, that operated in such a way as to send a message cost a certain amount of (arbitrary units called) crypts, but you could also package any number of crypts you currently posessed to the recepient, and the cost in crypts would be to reward the users who helped disguise the recepient, author, and content of the message.
please keep in mind that this isnt bitcoin, nor is it intended primarily as money. Its intended to be a secure, peer-to-peer cryptographic instant message system that allows users to transfer balances, the units representing computing power available to send secure messages. Receiving a message costs nothing.
would you use it, on your mobile phone? As a replacement for sms, or email? Assume state of the art functionality.