My GTD system consists exclusively in Outlook using the GTD Add-in and my Treo. Email consists of 90% of my communication and thus, I track NAs, projects and reference material mostly through email.
Using the GTD-Addin, I always "send and delegate" to people and mark it has the appropriate project and it goes onto my @Waiting For list. However, sometimes the recipient responds within minutes or it can be days. I definately want an @Waiting For task when it's going to be days, but it seems very uneccesary for an email that is going to get replied back within a few minutes. Any suggestions on this?
Also, when you have an item on your @Waiting For and you hear back from this person, how do you know that it actually is a task that you are waiting for? I tend to have gobs of @Waiting For tasks at my weekly review, that 99% of them have been done already. Do you simply not update your @Waiting For until the weekly review or do you try to keep it up to date all the time?