GTD functionality -- "43 (smart) folders"

One thing I’ve not seen any app do very well is easily provide two ways to look at your GTD data: by project and by date due. I am constantly filing away snips of email correspondence for later reference, and it’s very important that I be re-presented with this information as projects I’m working on pass through critical decision gates. DT will allow me to file by project (e.g. a collection) but there’s no way to ensure I will be forced to review the information at any later date.

As I hear smart folders are coming, I have been thinking they could be put in service to have the computer help you re-examine material at a later time, in a way that is analogous to the real-world “43 folders” of GTD fame.

The way that might work – I would tag a note as “re-review in one month,” and DT would then be in charge of tracking (an instance of) that item through various Smart Collections: Review Today, Review This Week, and Review This Month. I would want items to be sorted by date “due” within those collections.