In thinking about mindfulness, I'd love to be able to mark tasks as "not doing" but keep them with their time estimates. Along side a "how did I spend my time" report, how cool would it be to see a "what did I say no to" report. Comparing those would help me feel better about saying "No" because I can start to really see that the stuff in my "Done" report was really more valuable than my "Not Doing" report. It would also reduce some anxiety I have about actually "Deleting" tasks as if they never existed.