Not having a mandatory registration step definitely lowers the entry barrier for new users. Doodle (doodle.com) uses a similar technique for their polls. A user doesn't need to create a login to manage a poll, he just gets an admin URL and he/she can use that to edit/delete/manage the poll later on. Participants, meanwhile, get a different participant URL that does not have the admin options. Their pages are not served over HTTPS though, so I suppose it's not perfectly secure.