The odd thing, it seems to me, is that Joel and Jeff are sticking with the model of "lots of focused sites." I think that the existing tag system is sufficient to help people find the questions (and answers) relevant to them, and I don't see the downside to having "one big site" (like Quora).<p>Somebody ought to mock up a "Stack Universe" site, that integrates all of the data from the other sites, just to show what that would look like.