This looks pretty interesting. I've looked for annotation extensions in the past but they were too inconvenient to use and untrustworthy for privacy.

Edit: I've looked at their simplified privacy policy. I really like that they've limited how much money investors can make, and funds their company not by selling privacy but through their own revenue, grants, and steward ownership.

I use plaintext Markdown files to copy / pate interested links and some parts of content. This is just a text file so I can easily search a link using grep or whatever text editor.