Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.

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

Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.

TickTick - TickTickis a cross-platform to-do list app & task manager helps you to get all things done and make life well organized.

Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.

Remember The Milk - Remember The Milk is a task and time management application for mobile devices.