Make emacs store *~ backups files all in a single directory.

init.el

;;; Move the backup *~ files into a single backups directory instead of
;;; littering the filesystem with them. Also version the backups and only
;;; keep a finite number of backup versions.
;;;
;;; Read more, and get the required backup-dir.el here:
;;;   http://www.emacswiki.org/emacs/BackupDirectory
;;;
(require 'backup-dir)
(make-variable-buffer-local 'backup-inhibited)
(setq bkup-backup-directory-info
      '((t "~/.emacs.d/backups" ok-create full-path prepend-name)))
(setq delete-old-versions t
      kept-old-versions 1
      kept-new-versions 3
      version-control t)
(defun make-backup-file-name (FILE)
  (let ((dirname (concat "~/.emacs.d/backups"
                         (format-time-string "%y/%m/%d/"))))
    (if (not (file-exists-p dirname))
        (make-directory dirname t))
    (concat dirname (file-name-nondirectory FILE))))