Asana is a teamwork and productivity app with free and premium accounts, that lets you work collaboratively on projects. They have also just announced a native Android app. Originally, it was just an HTML5 web app.
Asana has some nice features including task lists, reminders, task requests, commenting on tasks and updates, tracking due dates, assignments, notes on tasks and more.
The Android app syncs with your web app account so everything stays organized.
Related:
kanban2go - free visual task management and organization
Getting Students and Teachers Organized - tips and resources
Evernote - super organizing, task list, note taking, project management app
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