At Jive, we use our internal instance of Clearspace for everything, we call it Brewspace (hey, we're in Portland with a brew pub on every corner!) We keep all of our planning documents, weekly status updates, and more in Brewspace. We use the TaskList macro to track completion of tasks.
The TaskList macro gives authors the ability to generate and track a simple list of tasks. Each line inside the macro body is parsed as a separate task. Each task will display with a graphic button for marking the task complete. When this happens, the userid is also recorded and displayed.
The TaskListMacro applies authorization policies based on the surrounding context. In simpler terms, if you are an author for the piece of content, you can also edit the tasks.
If you are interested in writing your own plugin or macro for Clearspace, you can find plenty of information in our documentation space.