YouCanBook.Me is a free scheduling tool that integrates with your Google Calendar. YouCanBook.Me allows people to book fixed blocks of time in your calendar. You specify the length of each block of time and the dates and times you are available. Visitors to your calendar click a block and enter their email addresses to reserve a block of your time. When a block of time is reserved you receive an email alert. Watch the video here to see a demonstration of YouCanBook.Me.