M-up/M-down 当前行上移、下移（根据org-mode的org-metaup/org-metadown代码提取出来的）
(defun swap-line-up ()
"Swap the current line with the line above."
(interactive)
(transpose-lines 1)
(beginning-of-line -1))
(defun swap-line-down ()
"Swap current line with the line below."
(interactive)
(beginning-of-line 2) (transpose-lines 1) (beginning-of-line 0))
(global-set-key (kbd "<M-up>") 'swap-line-up)
(global-set-key (kbd "<M-down>") 'swap-line-down)
"Swap the current line with the line above."
(interactive)
(transpose-lines 1)
(beginning-of-line -1))
(defun swap-line-down ()
"Swap current line with the line below."
(interactive)
(beginning-of-line 2) (transpose-lines 1) (beginning-of-line 0))
(global-set-key (kbd "<M-up>") 'swap-line-up)
(global-set-key (kbd "<M-down>") 'swap-line-down)
更多内容见评论（我好像比较喜欢这种方式来记零散的笔记:-）