Yes, site owners can run their own ads to monetize their networks. Technically speaking, they can paste and javascript code into their network header and sidebar, so they can add widgets, tracking code, ads or whatever they want.

Oh, from the site: "Monetize through Ads"

I like the ability to show a thumbnail in the posts.

One of our clients is http://photographersjournal.yonkly.com/home and they have a ton of cool photos. Check them out.