For me as a software developer / artist, I would love the ability of someone sending me money anonymously, and me sending him information back (e.g. serial number, download link, whatever) to his wallet.
Without him having to give me ANY ADDITIONAL information whatsoever.
Mr.Spread just explained a few posts earlier that this can't work like that, you need to broadcast atleast SOMETHING additional, your address will not suffice.
It can work by broadcasting this additional information but this will require some additional actions from those who will want to receive messages, what you want is simpler though, by signing transaction you make your public key known, this should be enough to encrypt a message. But some people may send you money not from the wallet but from an exchange which will probably just ignore such messages.
If you could pull that off i would be personally overwhelmed. Digital cash must have an equally anonymous (optional) way to send a msg.
It's naive to think we can use ecash over the internet now and stay anon. If you want to buy a laptop with "Spreadsend"or"Darksend" you have to input your personal details over the internet, which then tells the world your address, name, payment method.
We shouldn't underestimate the importance of an encrypted msg attached to a transaction.
If this is to be done, after "Spreadsend" is implemented would be perfect!