XCSoar JET App
OGN Viewer App
Slack App (Ask questions in SOSA's #xcsoar channel)
Maps
SOSA Airspace
SOSA Waypoints
Other misc. files
BONUS: Save a YouTube to MP3 for listening while driving.
Files App
Time Calculator App
GDL90 to NMEA Conversion
NOTE: It is temporarily impossible to load the necessary maps, airspace and turnpoint files using just the phone, it can now only be done using a USB cable to a computer.