I'm pretty sure he means he wants to have the links clickable server-side, not client-side like GreaseMonkey script functions.

You can check the includes\bbcode.php file, look for
PHP Code: 
function bbcode_second_pass_code($type, $code) 
Add the following line after the three lines starting with $code:

PHP Code: 
$code = preg_replace('@(https?://([-\w\.]+)+(:\d+)?(/([-\w/_\.]*(\?\S+)?)?)?)@', '<a href="$1">$1</a>', $code); 
note: I just looked around and did this quick and dirty, if there is another better way to do it - please post

EDIT: Fixed the RegEx that it also catches a dash (-)