this converts inputs to clickable links and does email addresses also - might not do exactly what you asked for
<?php
function makeLink($text)
{
$text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_\+.~#?&//=]+)',
'<a href="\\1">\\1</a>', $text);
$text = eregi_replace('([[:space:]()[{}])([url]www.[/url][-a-zA-Z0-9@:%_\+.~#?&//=]+)',
'\\1<a href="http://\\2">\\2</a>', $text);
$text = eregi_replace('([_\.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,3})',
'<a href="mailto:\\1">\\1</a>', $text);
return $text;
}
?>