[snaK9]

er, i have to go to work in about..30 seconds but PCRE should work.

$thetext = "go to ultrashock! or [LINK]http://www.identd.org/[/link]";
preg_replace("s/\[link=(.*?)\](.*?)\[\/LINK\]/gi", "<a href=\"$1\">$2</a>", $thetext);
preg_replace("s/\[LINK\](.*?)\[\/LINK\]/gi", "<a href=\"$1\">$1</a>", $thetext;
print $thetext."\n";