51:  Is there an equivalent to the `.' (dot) command of vi?
  
  (`.' is the redo command in vi.  It redoes the last insertion/deletion.)
  
  No, not really.
  
  You can type "C-x ESC" (repeat-complex-command) to reinvoke commands that
  used the minibuffer to get arguments.  In repeat-complex-command you can
  type M-p and M-n to scan through all the different complex commands you've
  typed.
  
  To repeat something on each line I recommend using keyboard macros.