This year we have discovered "navily" http://www.navily.com/
available for both android and apple.
We're referencing it extensively now for information relating to anchorages (it shows photo's, how protected an anchorage is from wind and swell, a colour coded anchorage rating, user feedback and information relating to the seabed and facilities nearby).
So far we've found the information to be very accurate but there is the facility to add your own comments or make corrections.
Additionally the app enables you to reserve a berth at a number of marinas....albeit this only runs to about 60 marinas at present.
Take a look because we think you'll find it a useful... ;-)