https://trello.com/

Whether it's managing a team, writing an epic screenplay, or just making a grocery list, Trello is your sidekick for getting things done and staying organized.

With Trello you can:

• Create boards to organize anything you're working on.
• Use them solo or invite coworkers, friends and family to collaborate.
• Customize workflows for different projects
• Add checklists of "To-Dos" on cards
• Assign tasks to yourself and coworkers
• Comment on items with your friends
• Attach files from Google Drive and Dropbox
• Upload photos and videos
• Reply to comments from Android Wear
• Display cards in a calendar view with the Calendar Power-Up
• Work offline and boards will sync automatically when reconnected