Action Plan is a project focused to-do list. It builds on the principle that any task or problem becomes easy to handle, when split up into manageable parts.
In Action Plan any task can be divided into sub-tasks, those sub-tasks can be further split up into other sub-tasks, and so on. This allows you to break down any activity into clear and concise steps, yielding a nice and very structured to-do list.
Progress is easily tracked in the graph view, where a burndown graph shows your progress, and gives a time estimate for the completion of the project.
There is also a desktop version (link can be found inside the app) but please note that there is no synch of data between the desktop and the mobile versions.