It would be exceedingly useful if the Web Clipper offered access to categories of available source information from a webpage: the DOM, Open Graph (see ogp dot me) and metatags, or information from the current URL itself (i.e. to extract categories for RESTful URLs that have a common pattern (i.e. /photos or /users).
For starters, it’d be very useful to access metatags like:
og:title
og:description
og:url
og:type