If websockets are not an option then you are left with Comet.
Client-side you could do something like this :
(function poll(){
$.ajax({
url: "url",
success: function(data) { /*display data*/ },
complete: poll,
timeout: 30000 });
})();
Which means an ajax request will be sent every 30 seconds.
This is not as performant as websockets but it works quite well.