Tired of having to decide whether to hit M-x occur, or whether SwitchingBuffers to the OccurBuffer Occur is more appropriate? Here is a defun to do either-or, inspired by MeatBall:HumaneInterface:

    (defun my-occur ()
      "Switch to *Occur* buffer, or run `occur'."
      (if (get-buffer "*Occur*")
          (switch-to-buffer "*Occur*")
        (call-interactively 'occur)))

Emacs reserves ‘C-c’ followed by an ordinary letter for users. You could bind occur to ‘C-c o’ as follows:

    (global-set-key "\C-co" 'my-occur)

This is a slightly different version - keeps the top window displaying the original buffer when typing ‘C-c o’ for the second time (that is, when both the Occur buffer and the original buffer are visible). The Occur buffer becomes active. Pressing RET (or mouse-2) on an item in the Occur buffer makes the original window active again and moves the point to the occurrence. Thus you can jump back and forth without the windows swapping.

    (defun my-occur ()
      "Switch to *Occur* buffer, or run `occur'."
      (if (get-buffer "*Occur*")
          (switch-to-buffer-other-window "*Occur*")
        (call-interactively 'occur)))

This key binding is the same as mentioned above, only written slightly differently.

    (global-set-key (kbd "C-c o") 'my-occur)

Also, once you’re done with the Occur buffer (when you no longer need that list), and the original buffer is active, here’s a key binding that allows you to kill the Occur buffer. If you only remove the window Occur, and not the buffer Occur (say, as happens with ‘C-x 1’), the next time you press ‘C-c o’, Emacs assumes you’re looking for the same regexp (unless you’ve pressed ‘z’ in the Occur buffer).

    (global-set-key (kbd "C-c C-M-o")
                    '(lambda ()
                       "Kill the *Occur* buffer"
                       (kill-buffer "*Occur*")

Here is a somewhat more sophisticated version of the above command extracted from module emacspeak-wizards — it sets a file local variable to the occur pattern.

I use this trick to then have files that contain slides in LaTeX to have an occur pattern that match slide header lines as an example.

   (defun emacspeak-wizards-occur-header-lines (prefix) 
     "If you define a file local variable called 
    `emacspeak-occur-pattern' that holds a regular expression that 
    matches header lines, you can use this command to conveniently 
    run `occur' to find matching header lines. With prefix arg, 
    prompts for and sets value of the file local pattern." 
     (interactive "P") 
     (declare (special emacspeak-occur-pattern)) 
      ((and (not prefix) 
            (boundp 'emacspeak-occur-pattern) 
       (occur emacspeak-occur-pattern) 
       (message "Displayed header lines in other window.") 
       (emacspeak-auditory-icon 'open-object)) 
       (let ((pattern  (read-from-minibuffer "Regular expression: "))) 
         (setq emacspeak-occur-pattern pattern) 
   (occur pattern)))))