More sites on different topics. Conferences. Books. Training courses. There are a lot of ways to monetize an enthusiastic audience that wants to learn.

I know I'm just an armchair quarterback, but there's a revolution in moving university courses online. Surely some of that will stick to the stackoverflow/serverfault/superuser crowd...

Aren't 'the investors' the guys the built it: Joel Spolsky, Jeff Atowood, and originally a small engineering team?

Edit: apparently I should have done just a few more searches before I answered this, it seems that SO did seek venture funding: http://www.joelonsoftware.com/items/2010/02/14.html