HTML5 Date Input doesn't work on Firefox #wtf
This one caught me by surprise today. Luckily, it's relatively simple to detect the missing functionality using Modernizr.js and use Datepickr instead.
$(function(){           
  if (!Modernizr.inputtypes.date) {
    $('input[type=date]').datepicker({
      dateFormat : 'yy-mm-dd'
    });
  }
});
