Just a few off the top of my head: Any major blog (TechCrunch, Mashable, Gizmodo) or media website, Stackoverflow's entire network. Most well-trafficked websites take advantage of advertising in some form and support a number of employees.

However, Quora probably doesn't have to stick with "pure" ad models -- and I don't expect them to. Just because they say they aren't focusing on monetization right now doesn't mean they're completely blowing it off. The Quora team is full of some pretty smart people who I'm sure know a bit about what they're doing.