I do this every day. I have a diary where I place everything in order to forget about them until the day it needs to be done. I have to-do lists that I fill out regularly and cross out regularly. I also write down any info like books or music that I want to download in the future, along with things I want to purchase in the future. I've only been doing this for the last year and it's honestly helped me turn my life around. I used to be an unorganized stoner. Now I'm a business man!

Haven't read the book so I'm unsure what GTD means exactly. I'll write it down on my books to read list ;)