In OmniOutliner, notes can be displayed "Inline" or "in Pane". I'd love to see OmniFocus incorporate a similar option at the *project* level. With "Display in Pane" enabled, when you click on a task in a project, the project's notes are displayed in the pane. That way you could jot task-specific notes and project-specific notes without having to switch the current focus.
Mockup:
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