myOpenLab - MyOpenLab is a platform for finished elements (program components) that can be linked together.
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
Challenged - Create and participate in video challenges of any kind.
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.
The Monthly Challenge App - Join collective challenges, set your own targets and track progress.
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.