Chris Button's apps hints

•  The photographers ephemeris (TPE) which shows you where the sun will rise and set (there is also an android version).
•  The app to help you with hyperfocal focussing is 'setmycamera' on apple or 'DOF Calculator' on android.
•  Lee Filters have created a useful app to show you what shutter speed to use when you've added an extreme long exposure filter. It's only for Apple at the moment although you can use 'ND Filter Timer' for android.  
•  The best app for tidal information is TidesPlanner.