BuddyPress.org

@FIQ – assume you are meaning a jQuery event, equivalent to something like a document.ready() that fires on Ajax load. Pretty sure there are some default jQuery events ready to AJAX activity.. can’t remember names off top of my head

[EDIT: take a look at the global jQuery ajaxSuccess, ajaxError, ajaxStart, ajaxSend, and ajaxStop events — there are also local versions]