Amie - GitHub for research and data science

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.

Todoist - Todoist is a to-do list that helps you get organized, at work and in life.

Airborn - Create and edit documents online without sacrificing your privacy