Editable Gmail annotation was the missing link for using Gmail as a full-fledged GTD organizer.

I use Gmail to collect and distribute information, but it is not good at letting me edit and organize the info in the emails because emails, once sent, are static. Gmail Notes are annotations attached to conversations that I write and update and can keep up to date as the conversations change my thinking.

The biggest win for me with Gmail Notes is that I have the ability to annotate a label, which means I can create a track an entire project from within Gmail by creating a label, annotating it with the project plan and the delegations I send out via Gmail, and then keep up to date whenever an email comes back.