Mobile - I often consume this kind of "clippable" content on a mobile device. It's limited in usefulness since it's just a browser extension (which doesn't exist on my Android)
Clipping UI - It can be frustrating to try and clip just the parts of a page that i want. The clipping box moves around seemingly randomly. I'd expect it to work similar to how a screenshot tool works, (a rectangular square on the screen) but it appears to be scanning for parts of the web page and then offering those parts as suggestions. This makes it difficult to just clip what I want.
Readability - On the "pinterest" board view (sorry - that's how I think of it) - the text is dramatically shrunk, and the headlines are often clipped. So I've got no idea what some of the clipped articles are about, unless I click them.
If there was a way to summarize the text instead of showing a thumbnail of the whole thing, it might be more useful. That technique (thumbnails) seems to work well on pics, but not on text oriented clips.
When I do click them, they appear in a lightbox view. The URL doesn't change unless I click through again to another view. It'd be good to have a linkable URL in lightbox views so I could share easier.
Nice work though, good luck with it. Also, I would love to hear more about developing your site in NodeJS .