Readwise is a read-it-later sort of service. You can put all kinds of things into it (articles from the web, PDFs, YouTube videos, podcast episodes). It also has an integrated feed reading experience, which is nice because you can highlight text in the feed items and then save the items to your permanent library.
It sends emails summarizing items you’ve saved recently and other emails to bring back to mind things you’ve highlighted previously.
There’s really a lot to the product and I’m a fan.