It looks like there are several ways to indicate an email variable on an email (e.g. high importance, from specific person), etc. It would be nice if you could designate an email category as a variable/trigger to create a planner task.
Also, along the same lines, I would love if there was a way for me to flag an outbound email (that I'm sending to someone) that this is a 'to-do' and that I'm expecting a response to it--and set the email so if I don't get a response after X-number of days, a reminder pops up to me (and the recipient?). I know there are ways to do this by using conversation view, and adding a reminder for the recipient, but it is not a 'one-click' thing to do.