Emacs function that removes duplicate rows in a region

emacs_uniq-lines.el

;; uniq-lines
;; ----------
;; This is something of a companion to the built-in sort-lines function.
;; Like the uniq utility, this removes duplicate lines from the region.  It
;; is best used after sorting a region.
;;
(defun uniq-lines (start end)
  "Removes duplicate lines from the selected region."
  (interactive "*r")
  (goto-char start)
  (beginning-of-line)
  (let ((last ""))
    (while (< (point) end)
      (let* ((bol (point))
             (eol (progn (end-of-line) (point)))
             (text (buffer-substring bol eol)))
        (forward-char)
        (if (string= last text)
            (delete-region bol (point))
          (setq last text))))))
(define-key global-map [(control ?z) ?u] 'uniq-lines)         ; Bind to C-z u

In Emacs 24.4, just use build-in command delete-duplicate-lines