Is there any other way to sign apps or games ?
because the way with the developer certificate request doesn't work any more
I mean that the request procedure on the website isn't supported any more for new users

All i can say is : temporary is no. use ur old key until it's expire.

Stay tune at HERE (http://www.ipmart-forum.com/showthread.php?t=146714). u will get the information when it's work again.