Sample code from O'Reilly jQuery Cookbook, chapter 4.

// chapter 4: jQuery Utilities
// Oreilly.jQuery.Cookbook.Edition.December.2009
// ==================
(function($) {
  $(document).ready(function() {
    $('a').filter(function() {
      var href = $(this).attr('href');
      // Normalize the URL
      if (!jQuery.support.hrefNormalized) {
        var loc = window.location;
        href = href.replace(loc.protocol + '//' + loc.host + loc.pathname, '');
      }
      // This anchor tag is of the form <a href="#hash">
      return (href.substr(0, 1) == '#');
    }).click(function() {
      // Special click handler code
    });
  });
})(jQuery);

// ====================================
(function($) {
  $(document).ready(function() {
    
    var months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
    
    $.each(months, function(index, value) {
      $('#months').append('<li>' + value + '</li>');
    });

    var days = {
      Sunday: 0,
      Monday: 1,
      Tuesday: 2,
      Wednesday: 3,
      Thursday: 4,
      Friday: 5,
      Saturday: 6
    };
    
    $.each(days, function(key, value) {
      $('#days').append('<li>' + key + ' (' + value + ')</li>');
    });
    
  });
})(jQuery);

// ====================================
(function($) {
  $(document).ready(function() {
    
    var months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
    
    $.each(months, function() {
      $('#months').append('<li>' + this + '</li>');
    });

    var days = {
      Sunday: 0,
      Monday: 1,
      Tuesday: 2,
      Wednesday: 3,
      Thursday: 4,
      Friday: 5,
      Saturday: 6
    };
    $.each(days, function(key) {
      $('#days').append('<li>' + key + ' (' + this + ')</li>');
    });
  });
})(jQuery);

// ====================================
(function($) {
  $(document).ready(function() {
    var months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
    months = $.grep(months, function(value, i) {
      return (value.indexOf('J') == 0);
    });
    $('#months').html('<li>' + months.join('</li><li>') + '</li>');
  });
})(jQuery);

// ====================================
(function($) {
  $(document).ready(function() {
    var months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
    months = $.grep(months, function(value, i) {
      return (i % 2) == 0;
    });
    $('#months').html('<li>' + months.join('</li><li>') + '</li>');
  });
})(jQuery);

// === === === === === === === === === === === ===
(function($) {
  $(document).ready(function() {
    var months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
    months = $.map(months, function(value, i) {
      return value.substr(0, 3);
    });
    $('#months').html('<li>' + months.join('</li><li>') + '</li>');
  });
})(jQuery);

// ====================================
(function($) {
  $(document).ready(function() {
    var horseBreeds = ['Quarter Horse', 'Thoroughbred', 'Arabian'];
    var draftBreeds = ['Belgian', 'Percheron'];

    var breeds = $.merge(horseBreeds, draftBreeds);
    $('#horses').html('<li>' + breeds.join('</li><li>') + '</li>');
  });
})(jQuery);

// ====================================
//['Quarter Horse', 'Thoroughbred', 'Arabian', 'Belgian', 'Percheron']

// ====================================
(function($) {
  $(document).ready(function() {
    var animals = $('li.animals').get();
    var horses = $('li.horses').get();
    $('#animals').append($(animals).clone()).append($(horses).clone());
  });
})(jQuery);

// ====================================
(function($) {
  $(document).ready(function() {
    var animals = $('li.animals').get();
    var horses = $('li.horses').get();
    var tmp = $.merge(animals, horses);
    
    tmp = $.unique(tmp);
    $('#animals').append($(tmp).clone());
  });
})(jQuery);

// ====================================
(function($) {
  
  $.fn.myPlugin = function(settings) {
    return this.each(function() {
      settings = $.extend({
        onShow: null
      }, settings);
      
      $(this).show();
      
      if ($.isFunction(settings.onShow)) {
        settings.onShow.call(this);
      }
    });
  };

  $(document).ready(function() {
    $('div').myPlugin({
      onShow: function() {
        alert('My callback!');
      }
    });
  });
  
})(jQuery);

// ====================================
jQuery.isFunction(document.getElementById);

// ====================================
// <input type="text" name="first_name" class="cleanup" />
// <input type="text" name="last_name" class="cleanup" />
(function($) {
  $(document).ready(function() {
    $('input.cleanup').blur(function() {
      var value = $.trim($(this).val());
      $(this).val(value);
    });
  });
})(jQuery);

// ====================================
var node = document.getElementById('myId');
node.onclick = function() {
  // Click handler
};

node.myObject = {
  label: document.getElementById('myLabel')
};

// ====================================
$('#myId').data('myObject', {
  label: $('#myLabel')[0]
});

var myObject = $('#myId').data('myObject');
myObject.label;

// ====================================
// < div id = "time" class = "updateTime"></div>

// === === === === === === === === === === === ===
// Listen for new data
$(document).bind('setData', function(evt, key, value) {
  if (key == 'clock') {
    $('.updateTime').html(value);
  }
});

// ====================================
// Update the 'time' data on any element with the class 'updateTime'
setInterval(function() {
  $(document).data('clock', (new Date()).toString());
}, 1000);

// ====================================
(function($) {
  $.fn.myPlugin = function(options) {
    options = $.extend({
      message: 'Hello world',
      css: {
        color: 'red'
      }
    }, options);
    return this.each(function() {
      $(this).css(options.css).html(options.message);
    });
  };
})(jQuery);

// ====================================
var obj = {
  hello: 'world'
};

obj = $.extend(obj, {
  hello: 'big world'
}, {
  foo: 'bar'
});

alert(obj.hello); // Alerts 'big world'
alert(obj.foo); // Alerts 'bar';

// ====================================
$('div').myPlugin({
  css: {
    color: 'blue'
  }
});

// ====================================
$.fn.extend({
  myPlugin: function() {
    options = $.extend({
      message: 'Hello world',
      css: {
        color: 'red'
      }
    }, options);
    return this.each(function() {
      $(this).css(options.css).html(options.message);
    });
  }
});

// ====================================
var obj1 = {
  foo: {
    bar: '123',
    baz: '456'
  },
  hello: 'world'
};
var obj2 = {
  foo: {
    car: '789'
  }
};

var obj3 = $.extend(obj1, obj2);

// ====================================
// { foo: { car: '789 }, hello: 'world' }

// ====================================

// ==================