phpeveryday.com

<?php

function activateURL($text){
  return eregi_replace("([[:alnum:]]+://[^[:space:]]*[[:alnum:]#?/&= +%_:]]*)","<a href=\"\\1\">\\1</a>",$text);
}

$test = "This is my url: http://phpeveryday.com/articles/Zend-Framework-Intro-Explaining-Anatomy-of-Zend-Framework-Application-P470.html. It is so lazy to put tag on that url. So, I just use simple activateURL. It work!";

echo activateURL($test);
?>

Hope, it help us.