The only trouble I have with GTD is that there is NO END to how you can implement it! ...As evidenced here by the shear volume of post (just on how to implement a Tickler File)! As a result, I have found myself bouncing from solution to solution, constantly in pursuit of the most efficient implementation (maybe I'm just neurotic that way). Anyway, my latest kick is with MS Entourage, which seems to be lasting pretty well.
If no one minds... one more implementation, you are welcome to try out a set of AppleScripts I wrote that creates an Email Tickler for Entourage. You can read about this at:
Hopefully this helps (more than it frustrates),