I read on HN that Quora pivoted and joined Ycombinator, more for for exposure I guess? It was basically a StackOverflow alternative with real names. Will be interesting to see how their piviot to something else turns out.
You can read some answers as to why Quora joined YC here: http://www.quora.com/Why-did-Quora-join-the-2014-Y-Combinato....