Flexibits, the developer of Fantastical, calls the app "the Mac calendar you'll actually enjoy using," and darned if it isn't right. In a lot of ways, this calendar replacement reminds us of Siri. For instance, you don't click specific days and times to set appointments. Instead, you just type your sentence in plain English, and the program figures out what you're trying to schedule. Fantastical can work with Calendar, iCal, BusyCal, Entourage or Outlook. While Fantastical's functionality somewhat overlaps with that of Clear, we preferred Clear for simple daily tasks, and Fantastical as a robust appointment system.