I am not a big "GTD-er" but there is a concept from it that I really like. It is that, no matter how big, amorphous, or complex a task is, one can always ask: "What is the next thing to do?" and "How long will that thing take?".
Is there a plugin that adds a field one can use for this information?
It would be really powerful to be able to look at a list of all the tasks I have and see the 10-15 word "NTTD" fields.