Yesterday Kototama commented about another neat paredit addition: duplicating sexps. This is my take on that:

(defun paredit--is-at-start-of-sexp ()
  (and (looking-at "(\\|\\[")
       (not (nth 3 (syntax-ppss))) ;; inside string
       (not (nth 4 (syntax-ppss))))) ;; inside comment

(defun paredit-duplicate-closest-sexp ()
  (interactive)
  ;; skips to start of current sexp
  (while (not (paredit--is-at-start-of-sexp))
    (paredit-backward))
  (set-mark-command nil)
  ;; while we find sexps we move forward on the line
  (while (and (bounds-of-thing-at-point 'sexp)
              (<= (point) (car (bounds-of-thing-at-point 'sexp)))
              (not (= (point) (line-end-position))))
    (forward-sexp)
    (while (looking-at " ")
      (forward-char)))
  (kill-ring-save (mark) (point))
  ;; go to the next line and copy the sexprs we encountered
  (paredit-newline)
  (yank)
  (exchange-point-and-mark))

Like Kototama says in his blogpost, duplicating a line is very useful, but sometimes it leads to invalid sexps. In the blogpost he shows a snippet that will duplicate the sexp after point. I immediately realized I had really been wanting this.

The version listed here is a little modified: It will duplicate the sexp you are currently inside, or looking at, or looking behind at. So basically, point can be in any of these positions:

  |(my sexp) ;; in front
  (my| sexp) ;; inside
  (my sexp)| ;; at the end

Insta-useful!