XE - great currency app, lots of currencies all at once
Flightboard - flight information boards for airports all over the world
Dashlane - 256-bit encrypted password app, they dont store your data on their servers!
Dropbox
Maps.me - great overall app for offline maps and navigation (drove from Lake Como to Cinqueterre recently with no problems)
Citymapper - great for individual cities, not heaps of cities
Tripadvisor - has offline downloadsfor content
Vivino - for the alcoholics out there
Whatsapp
Google translate - has offline option for translation, point your camera and it'll translate things even offline
Emergency+ - never had to use this fortunately but gives exactly GPS location and can call Aussie emergency services
and finally
Qantas app - cant leave home without it