Lots of sites have this "hovercard" style pattern on links which shows you a cut-down preview of the page behind the link - often times with additional interactions.

I wonder if anyone has any more examples? Especially sites which do this (display a rich tooltip) on non-links.

A screenshot of a "Hovercard" on GitHub, showing the "W3C" org avatar hovered over, which has popped open a rich tooltip showing more information about the org - including their location, member count, the number of repositories, and their verified status.A screenshot of the Wikipedia "popover" article. The link "Yorkshire Pudding" has been hovered, which has displayed a preview-card with a small except from the Yorkshire pudding page, including the image on that article.Hovering over a username on mastodon renders a "hover card" - in this case hovering over the avatar of user "keithamus" shows the username, handle, description, as well as links and follower count - and an "edit profile" button.
0

If you have a fediverse account, you can quote this note from your own instance. Search https://indieweb.social/users/keithamus/statuses/114415997240973415 on your instance and quote it. (Note that quoting is not supported in Mastodon.)