This is something that many other forums have and I would love for Flarum to have.
Pretty much paste a link and Flarum would use some kind of a mechanism to get information from that link/page to use in the post as a small quick info box.
If this could be an extension you can use CURL/Guzzlehttp or embedly the service.
Be able to use images as thumbnails in the post if they exist.
Just a thought.
