Solution using Function#bind():
http://jsfiddle.net/RQncd/1/
for (var i = 0; i < 5; i++) {
$.ajax({
url: '/echo/html/',
method:'post',
data: {
html: 'Ajax data'
},
success: (function (i, resp) {
$('#success').append(i);
}).bind(null, i)
});
$('#outsideAjax').append(i);
}