Pulls today's events from GCalendar by using getEventsForDay.

GASEventsToday.gs

/* In case of inconsistencies - Check:
https://stackoverflow.com/questions/11870304/google-apps-script-geteventsforday-returns-invalid-recurring-events
*/ 
function EventsToday() {
var user = Session.getActiveUser().getEmail();  /*The mail will be sent to the user running the script*/
var startOfDay = new Date();
var events = CalendarApp.getDefaultCalendar().getEventsForDay(startOfDay);
var evlist = 'Hey!! These are the events you have for today<br>';
Logger.log('Number of events: ' + events.length);
  
  for(var e = 0;e<events.length;e++){
    /*Translates event time into readable time*/
    var HumanTime = Utilities.formatDate(events[e].getStartTime(), Session.getScriptTimeZone(), "HH:mm:ss dd/MM/yyy");
    evlist = evlist+"<p><b>"+HumanTime+"</b> <br>";
    evlist = evlist+"<i>"+events[e].getTitle()+"</i></p>";
  }
  
evlist = evlist + '<br> Timestamp  ' + startOfDay
Logger.log(evlist);
  
MailApp.sendEmail (
    user,
    'Your schedule for today ' + Utilities.formatDate(startOfDay, "GMT", "yyMMdd"),
    '',
    {htmlBody: evlist,name: 'Automated mail'}
  );
  
}

Is it possible to have it grab events from more than one calendar?