I know that Doodle.com (easy way to schedule a meeting time for a bunch of people and–much appreciated by me–does not require any sort of registration for participants or administrators) is old news to many people. Not sure that everyone realizes that it can be used to schedule a bunch of individual meetings too, though. This makes it awesome for instructors who need to schedule student conferences (or presentations, etc.). No paper sign-up sheets, and no wasted class time. Just click, under “Settings,” the boxes “Participant can only choose one option” and “Limit the number of participants per option” (to one). Then sit back and watch them sign up.