The Eisenhower time management method [1][2][3] is a very practical and intuitive method of managing one's time. It might have a place in Orage, too.

The main idea is that you classify your TODO tasks as Urgent & Important, not urgent & Important, Urgent & not important, and not urgent & not important. 

I think that adding such functionality would be relatively straightforward in Orage. At a minimum, when adding TODO tasks (or even Events), there should be two check boxes, Important and Urgent, both enabled by default. In the GUI this could
be translated, say, as red for 'UI', orange for 'uI', yellow for 'Ui' and green for 'ui'---even though this would modify the existing color scheme for TODO tasks. You could also add a View > View Tasks menu item that would pop up a window displaying a list appropriately sorted and using intuitive headings. Additionally, it could also come up with an actual matrix displaying the TODO tasks (somewhat similar to the current info box).

To avoid complicating things for those who just want a simple, minimalist TODO, we could provide a 'Use Eisenhower method' option in prefs (enabled or disabled by default). This way users who don't need 'advanced' time management techniques would be spared of the more complex color scheme, parameters, etc.

[1] https://en.wikipedia.org/wiki/Time_management#The_Eisenhower_Method
[2] http://www.easytimeplanner.com/concept.aspx
[3] http://www.bing.com/images/search?q=The+Eisenhower+matrix&go=&qs=n&form=QBIR&pq=the+eisenhower+matrix&sc=0-0&sp=-1&sk=