Adding note to email

I would like to suggest a function (right click?) which allows the user to add a note for own comments to an email. My business has very little repeat business with no need for the CRM module so when an enquiry comes in I'd like to easily add a note to the email stating actions ie., 'quote for $85.00 sent 31.1.12' or 'draft sent with changes' - not necessarily a contact card as such but somewhere where I can make notations on actions and the like. Customer calls for follow up - bam! there it is without having to click through threads.