Shared account and a unified experience between different Discourse instances

Now we've seen so many projects/companies use Discourse as a discussion forum. However, I often find it a little cumbersome to register accounts for each website (though SSO alleviate this pain a bit) and setup user profile and preferences or something alike.

I wonder, like opting in for 'Discourse Discovery', could we add an option for site owners to opt in sharing account info with CDCK? Basically it could mean adding an SSO option like 'Login with Discourse'. Moreover, to integrate more tightly, we can share user info and preferences between different communities like what Reddit does. It could be even better if users can access their aggregated activities/bookmarks/likes/replies data in one page.

Discuss this on our forum.