CheatKeys - View Windows keyboard shortcuts in the current application.
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
KeyCue - Menu shortcuts are supposed to provide quick access to frequently used menu commands.
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.
cheat.sh - The only cheat sheet you need Unified access to the best community driven documentation
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.