My Emacs Productivity Tricks/Hacks
The one thing I consistently do in emacs that shocks my coworkers -- is running this (custom) function, that I call "arrayify":<p><pre><code>  (defun arrayify (start end quote)
    "Turn strings on newlines into a QUOTEd, comma-separated one-liner."
    (interactive "r\nMQuote: ")
    (let ((insertion
           (mapconcat
            (lambda (x) (format "%s%s%s" quote x quote))
            (split-string (buffer-substring start end)) ", ")))
      (delete-region start end)
      (insert insertion)))
</code></pre>
What it does: Given a list of strings separated by newlines (commonly, something copy-pasted from a table) like:<p><pre><code>  josh
  sam
  jed
  C.J.
  toby
</code></pre>
You select the text, and run "arrayify". You can optionally provide a quote character and, in about half a second, get to:<p><pre><code>  "josh", "jed", "sam", "C.J.", "toby"
  </code></pre>
This is incredibly useful for taking lists of IDs, or email addresses, or whatever, and transforming them for pasting into documents, or emails, or "in" clauses in SQL, etc.<p>It is <i>unbelievably</i> useful.