jQuery: outer html()

Just use standard DOM functionality:

$('#xxx')[0].outerHTML

Or a bit simpler with .prop():

$('#xxx').prop('outerHTML')

outerHTML is well supported - verify at Mozilla or caniuse.

No siblings solution:

var x = $('#xxx').parent().html();
alert(x);

Universal solution:

// no cloning necessary    
var x = $('#xxx').wrapAll('<div>').parent().html(); 
alert(x);

Fiddle here: http://jsfiddle.net/ezmilhouse/Mv76a/

Create a temporary element, then clone() and append():

$('<div>').append($('#xxx').clone()).html();