In a previous post I talked about creating an Outlook Task from OneNote. The connection between these two applications works both ways. You can also create a task in Outlook and then use the Connect to OneNote button to create a page for that task in a notebook.
You can then use that page to add files, any other contributing notes, etc. Any time you select the task in the future and click the OneNote button, the specific OneNote page opens.
This also works for task lists that you have created on SharePoint, and then linked to your Outlook. You can connect tasks from those SharePoint lists directly to your OneNote files.
The result of this is a complete task management system, including projects, tasks and notes, all into one powerful system.