When I consider what it means to be productive, I need to think about the people I work with, and not just myself.
Though I might get something off my desk and to-do list more quickly by sending an e-mail or walking across the office, I should keep in mind that such isn't necessarily better for the people I'm working with. Though it might be more challenging for me, sometimes the best thing to do is to wait till tomorrow or longer to send the e-mail about the lower priority item that needs to be addressed sometime down the road. At its basic level, this means evaluating whether I am just passing things on to others in order to get them off my plate, or whether I honestly think that it is time for them to consider the issue in their own planning.
On the other hand, some people might want to know about ideas as soon as possible, so they can plan far into the future. If I don't send them my idea now, they may be resistant to reprioritizing their already planned schedule to work it in.
It really makes me wonder, what does it mean to discuss all of these productivity enhancing systems in isolation, with a focus on the individual, and on what the individual can get done in a day? It seems like a repeat of what I consider to be a mistake in much Western (and other) philosophy, the focus on the atomistic individual, accompanied by negligence toward the effective consideration of social relationships.
This applies to more than work in the office; it applies to artistic collaboration as well. I need to "honor the process" when pushing collaborations with others; do a better job of listening and finding different ways to work with people. I've not been a very popular partner in these kinds of projects, and maybe this has something to do with it. It's a very difficult thing.
(By the way, the sought-after way to bring all these different communication methods together is called Emacs as far as I'm concerned. It manages my e-mail, newsgroups, some RSS, IM, IRC, music, writing, files, planning, bookmarks, appointments, etc. All completely scriptable, scorable, sortable, lovable.)