FoundationDB endlessly interests me and even though the record layer is nice, my dream would be a proper SQL layer. I've been experimenting with making Postgres run on top of FoundationDB, effectively making Postgres a stateless layer itself, and it actually works surprisingly well as a POC.
Unfortunately nothing yet. Feel free to hit me up at the email in my profile and I'll let you know if I do write something up.
Another pretty cool fact is that I've so far managed to build the entire thing without having to fork Postgres, only using all the built-in extension points which are really great.