[al_f]

I really try to think of contexts in terms of "what do I absolutely need to have to accomplish this task?". If you think of them in this way (and you're rigorous about your processing) there is really very little if anything that needs multiple contexts. For example, in Brian's example the only essential thing there is Sue, since it doesn't matter how he communicates with her, so I'd put it in the @agendas context under Sue, or in @Sue if I had it set up that way. In ptone's phone call example, do you actually need to refer to anything that's in your office when making that call, or do you absolutely need to use work's phone line (if it's an international call, for example)? If so, it goes in @office. If not, it goes in @calls as all you need is any phone. I invite other problem cases to see if I can knock them down. :)

I disagree with SteveW's definition of contexts - I think that mood, days of the week and goals aren't contexts. For me, mood/energy is one of the factors you use in choosing what to do (along with context, time available and priority). Tasks specific to a day of the week go on my calendar ("hard landscape" as David Allen calls it) for that day. Goals go on my 20,000ft, 30,000ft etc. lists as appropriate depending on their timescale and scope.

Finally, how would adding tagging to OF make things simpler? Isn't it just another layer of stuff to fiddle with?