Another solo effort of mine was the Trifecta Mapping Utilty Device.
The following images are screen grabs from a 10" Samsung Tab running a prototype version for local GIS merchants Trifecta.
Off-line satellite cache with optional RTC enhanced GNSS walking modes. Here with data from Spar300 magnetic sampler from Optimal Ranging.
Satellite tiles were switchable between Google, Bing and OSM sources.
The topographical data is from local agency LINZ overlaid for test purposes on google maps activity to ensure WGS84 conversion of spherical geo-coordinates are correctly transformed to metric display space by the haversine formula.