Where do book lovers hangout on the Internet?
They don't hang out on the internet, they are reading books :D
More serious answer: Goodreads.
Still Goodreads, but damn, that site is ugly. But this is where my community is hanging, so...
(From my personal experience) I've visited:
- https://readernaut.com/ (don't know if it's still active)
- http://lubimyczytac.pl/ (PL)
Nowdays Facebook Groups took over (mostly due to their convenience and ease of use).
Goodreads, Amazon, and Audible are the only book related sites I visit.
Producr Hunt is a good place to show/promote book related websites! I had mediocre succes with wits.io where i got almost 100 paid signups via product hunt. I am also working on a telegram community but havent posted it on ProductHunt yet, wits.chat