> When I’m reading something and don’t understand a particular word or want to know more about a quote, when I select it, my computer should search across everything I’ve read and some small high-quality subset of the Web to bring me 5-10 links<p>IIRC Google Books (used to?) do something similar. Often I'd come across a word or phrase I did not know, I'd highlight it and the dictionary definition would show up in a small modal. I really enjoyed that feature.