I agree that modifying Outlook today would be nice, but probably not worth the effort of going to some sort of custom HTML solution.
One alternative that I have implemented recently in Outlook is to have a series of customized views that combine several of my Action/Categories such as @Calls, @Home, @Computer, etc. as a single "Home context" view (since all of these contexts are available at home), sorted by priority in the case of one view, and another identical one sorted by Action, so they appear together.
I have other context-based views for Work - Office and Work - On the Road contexts and they work very well.
Hope this helps,