To be exact I am suggesting:

Whenever you add a webpage to the plex by dragging it's icon in the URL bar of a web browser to the plex, there should be an option such as a set of keys (e.g. holding down shift while dragging & dropping) that would cause PersonalBrain to actually capture the HTML and associated pictures from the webpage and place them in the "Notes" section.

Furthermore, I think this option should be further customized to allow one the option to actually attach the HTML file of the page you were looking at to the actual thought, such that it can be viewed by the system's default HTML browser rather than in the "Notes" section.