Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
TaskPaper - Plain text to-do lists for Mac
Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
Listy Beta - The things you love, privately saved and beautifully listed
BibDesk - BibDesk is an organizational software created to help you edit and manage your bibliography. It keeps track of your bibliographic information as well as said information's associated web links and files. Read more about BibDesk.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.