Many users will be members of many sites of workspaces in SharePoint, and as you probably already know, every Site or Workspace usually contains a Task List. This means that you may have tasks assigned to you in Document Workspaces, Meeting Workspaces, and Team Sites.
The below image displays an example Site Collection with Tasks assigned to somebody. This illustrates how the tasks could be rolled up to the top level site using the Lightning Conductor Web Part.
The Tasks that are rolled up to the top level site can also be filtered. Common filters allow us to show all outstanding tasks, all completed tasks or tasks assigned to the currently logged on user. You can also group the tasks by Status providing you with expand and collapse capabilities.
Several views allow you to tweak the way the results are displayed. You can use the Tasks list Default View which looks just like one Task list although it is an amalgamation of many lists, use the Grid View allowing you to choose the displayed columns, and add aggregate functions, grouping and sorting. Or you can use the XML view where you need to develop with it, but could display Key performance Indicator traffic lights displaying the completed tasks in Green, and non-completed in red.
Below is a screenshot of the Lightning Conductor Web Part rolling up tasks
