I found these custom rims on ebay. I've never seen anything like it before. I think they're pretty cool, but I don't know if they look good on a stang. I'd buy them just for the "cool" factor. It would probably be an interesting thing to have at a show. Don't really know how safe the rims are...
http://cgi.ebay.com/ebaymotors/Ford-Mustang-Custom-Wheels-17-X-9-Late-Model-Show-Car_W0QQcmdZViewItemQQcategoryZ43957QQitemZ8019857399QQrdZ1
http://cgi.ebay.com/ebaymotors/Ford-Mustang-Custom-Wheels-17-X-9-Late-Model-Show-Car_W0QQcmdZViewItemQQcategoryZ43957QQitemZ8019857399QQrdZ1