I ran across this list on the X100S short cuts on a forum by a guy named "MikeH" and thought that it was useful.  I'm definitely ingraining some of these into my brain to make my life a bit easier when out and about with this little beast of a camera. B-)

I have listed them below the image in order of what I would use most (or the most useful to me) to least.  Have fun X-shooting!

Fujifilm X-E1 | Kipon Adaptor | Nikkor 50mm F1.4D

• Press and hold DISP/BACK button to activate (or deactivate) the camera’s Silent Mode. When this mode is turned on, the X100S functions quietly and inconspicuously. It won’t make any artificial noises and it abstains from using both the flash and the AF-assist lamp.
• Pressing the DISP/BACK button while selecting an AF field in AF-S Area mode will immediately select the central AF field.
• Press (but do not hold) the command dial to enlarge the current image to inspect its sharpness. This works in both MF and AF modes. Rather than selecting a function in the shooting menu by pressing the OK button, you can press the shutter button halfway down. Pressing the shutter button halfway down while in playback mode switches the camera directly into shooting mode. You can wake the camera by pressing the shutter button halfway down as well.
• Double-tap the macro button to switch between normal and macro modes.
• Press DISP/BACK in shooting or playback mode to change the view of the currently active display. This means that in order to change the view of either the OVF, the EVF or the LCD, either the OVF, EVF or LCD must be active when you press the button. You can select the display you want to change with the VIEW MODE button. Alternatively, use the eye-sensor to activate a display by looking through it, then change its view with the DISP/BACK button. 
• Press and hold the Q button for a few seconds to clearly increase the brightness of the LCD. This can be quite helpful when operating the camera in bright light, like on a sunny day.
• Press and hold the MENU/OK button down to lock or unlock the arrow keys and the Q button.
• A long press of the Fn button will bring up the Fn button’s configuration menu, where you can assign one of several functions.  The Fn button is defaulted to ISO setting.
• To check (or upgrade) the firmware version of the camera, press and hold the DISP/BACK button while switching on the camera. In manual focus mode, press the AE-L/AF-L button to initiate an autofocus run.