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.