Check and uncheck group of checkboxes

As seen on gmail, when you click on the checkbox on table head it selects all checkboxes in the table. Simple, yet useful!

$('#selectAllCheckbox').click(function(){  

       if($(this).is(':checked')){
             $(this).parents('table').find('input[type="checkbox"]').attr('checked', true);
             }
       else{
            $(this).parents('table').find('input[type="checkbox"]').attr('checked', false);
        }
    });