AJAX push

We're writing a webserver in our spare time and we are now at the point where we want to explore new web features. What is the best way to do full asynchronous communication with javascripts? Can we just periodically check in javascript if we've received something? Or is this only possible if you do a XMLHttpRequest beforehand? Are there other methods?

>>10
WebSockets are currently removed from all browsers due to ``security''. You can use Flash though, it has something similar to WebSockets. But your flesh will rot if you use Flash for that.

What this guy wants is called ``COMET''. Check again in 10 years for more elegant solutions.