Automatic Notes Reminders when visiting a certain webpage

It would be great if there were a feature that allowed you to attach a note that would pop up when you visit a certain page. For example, you have a coupon code for your next order from that site. By the time I return to the site a week or month from now, I forget about the coupon. But if you could create a note that would pop up a reminder the next time you visit a site, that would be pretty cool!