Open-source aviation mappng program, no-nonsense basics with minimum bells and 
whistles.  Includes geo-referenced airport diagrams and approach plates.  
Source on https://github.com/mrieker/WairToNow

App covers areas covered by US charts, including sectionals, terminal area 
charts, helicopter charts and what's left of world charts.  Also included is 
mapping via OpenStreetMaps for walking/biking to nearby $100 hamburger stands, 
as well as georeferenced approach plates and airport diagrams.  Also provides 
OpenStreetMap-backed runway diagrams for all airports, though they are 
primarily used for those airports that don't have official FAA-provided 
airport diagram plates.  Approach plates include an optional on-screen DME 
display that the user can configure.
