Well the question's in the title, Stack Overflow Talent seems like an obvious candidate to include in the main list of sites on the stack - or perhaps as a side-bar advert. I don't know about the revenue stream here, but the usual off-topic question on meta resulting in links to all sites should include links to those relevant to profit generation, not to mention relevance to the query.
I've only the most recent missed opportunity for reference, but I'm sure there are others.