Google Calendar - Appointment Slots

Here's something that's been around for a while but I didn't know it existed, and it's great!  Appointment Slots is a tool baked into Google Calendars which allows you to designate a time period, with incremental time slots, for people to self-select a meeting time with you.  This would be useful for teachers setting a time for students to meet or parents for conferences.  The process for creating one is as simple as creating an event.

Here is a Quick Tutorial from Google