Liz Gannes writes:

[PandaWhale] does some nifty tricks around aggregating threads of conversations from elsewhere on the Web, rather than trying to be a new destination unto itself.

So, for instance, PandaWhale users can import a Facebook or Twitter post, as well as all the replies on that platform, onto a single page and combine it with a discussion on that topic on PandaWhale. All the site's conversations are public. You can see an example here.

Tip of the hat to Liz!

Bonus points for linking to the How to Become Great convo.