GPS Status & Toolbox - Display your GPS and sensor data: Shows the position, number and signal strength of GPS satellites.
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
iHunter Alberta - iHunter Alberta is an amazing mobile application offered by Inside Outside Studio Inc.
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
Trail Sense - An Android app which uses your phone's sensors to assist with wilderness treks or survival situations.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.