if i am on a site, i should be able to open/create a text file linked to it, so i could put notes about the site, like "charges too much shipping" "This is where i got the great kale seeds" you could use whatever editor you have loaded anyway. being able to pick one would be a nice bell/whistle. files would be where the user said, like docs/firefox-notes/ and named like:
http//somewebsite.com becomes
somewebsite.firefox.note