It would be nice if the password (or more likely a key derived from the password) could be attached to the URL (in the hash so that it isn't sent to the server

It would be nice if the password (or more likely a key derived from the password) could be attached to the URL (in the hash so that it isn't sent to the server of course) and there was support for generating a random password/key. This way you could just send someone a URL and the transfer would start as soon as they open it. Human-understandable passwords have their place but if I need to send the signaling server info anyways I may as well transfer the encryption info in-band.