It would be great if the ability to annotate websites. This annotate feature should be toggleable and allow users to draw, highlight, erase what they've drawn on the website and save what they've drawn to a PDF or image.
This function would be useful for a verity of reason/people. For example: this would allow (online) teachers to more easily work through examples on a website, or draw an example on a website for their students. It would also be useful for students working out some problems on a website, as well as general users who want to make notes as they scroll or work something out on a website.
I know that you could simply take a screenshot of the website or save as a PDF and then edit the image/PDF, but that's not as convenient and with the image option it would be more difficult if you wanted to be able to scroll up and down the website while keeping your annotations in place.