Checkvist is a web app that lets you create to-do lists with numerous nested sub-tasks. You can then share your lists with collaborators, update them and add notes to them. You can track the progress of your projects, share files, assign due dates and export the lists in a variety of different formats.
A robust list app for geeks
Unlike most task management apps, Checkvist is very keyboard-centric. Instead of clicking and dragging icons around the screen, you can work primarily with keyboard shortcuts. You can also include text formatting and even code within your tasks using the app's markdown feature. All of this points toward its target audience: coders, writers and others who think best with their fingers on the keyboard. The interface is simple and easy to use, especially once the various keystroke sequences of the shortcuts become second nature. Once you've created a list, you can update it easily, share it with others and set a range of different preferences relating to it. A basic account is free, but for some features, such as file attachments, you'll want to upgrade your service to the paid version.
A unique approach to task management
If you're just planning your grocery lists, Checkvist might be too much bother to learn, but if you want a way to manage complex tasks and prefer to think as you type, it's definitely worth checking out.