ob / while / sleep

[Dangermouse]

Lets say i wanted to echo "hello" every second, how would i do this? I have tried it in a while(true) loop and using some ob flush'ing, but it just wont print it

[Dangermouse]

I got it!

<?
set_time_limit(0);

while(true) {
   echo "Hello<br>";
   flush();
   ob_flush();
   sleep(1);
}
?>

[Daijoubu]

What is this for?
I hope you aren't going to make it generate infinite js popup