Most effects from the UI contain the following

if(o.callback) o.callback.apply(this, arguments); Callback

the given options aren't in the object o but in o.options

so adding

if(o.options.callback) o.options.callback.apply(this, arguments); Options Callback

gives the possibility to do

$(elem).effect('shake', {direction: 'up', times: 2, callback : function(){

$(elem).effect('shake', {direction: 'left', times: 2});

}});