[otrs] "No Time to Register - Submit a ticket right away" option

I have seen a useful feature on other helpdesk systems at the login screen - a "No Time to Register - Submit a ticket right away" option which just asks for a username and email address and allows the user to submit a ticket straight away without waiting for a password to be emailed. In these cases, a password does get emailed so that the user can come back to the system at a later time, but the advantage is that the user can submit a ticket straight after registering without waiting for a password. Maybe a captcha can be used to avoid spam. Any ideas how this could be implemented - if at all ? Lee