See http://foliotek.github.com/AjaxQ for a demonstration and documentation
$.ajaxq
follows the $.ajax options and return value, with an extra first parameter (the queue name).
$.ajaxq(name, opts);
$.getq
follows the $.get options and return value, with an extra first parameter (the queue name).
$.getq(name, opts);
$.postq
follows the $.post options and return value, with an extra first parameter (the queue name).
$.postq(name, opts);
$.ajaxq.isRunning
returns a boolean representing if any requests are currently running (in any queue.
$.ajaxq.isRunning();