i think the problem i have is that you need a perfect portable hardware and a perfect gtd software. flexible enough for you to review from a broad perspective, projects or area of responsibility wise and also enable u to focus on the next action. there is no straight forward way.
if you want portable and be able to get a broad perspective a mind mapping tool that shows progress like ithoughts is possible. but really what i am hoping on is something more sophisticated.
no one have managed to translate those 50,40,30 thousand ft stuff and projects that contains more projects into a nifty GTD program.