Do want

darrik-nai-curly-special.el

(defadvice newline-and-indent (after darrik-nai-curly-special activate)
  "Do something special when RET between {}."
  (when (eq (char-after) ?\})
    (let ((pos (point)))
      (if (search-backward "{")
          (progn
            (goto-char pos)
            (newline)
            (indent-according-to-mode)
            (previous-line)
            (indent-according-to-mode))))))

test.c

 
/* | is cursor position */

if(blaha) {|} /* if I press enter while at | I want: */

if(blaha) {   /* this */
  |
}