Those valuations are for the actual domain name newschoolers.com and are based on traffic metrics, they have nothing to do with the underlying business, and are probably overinflated (domain names are not as relevant now anyway).
Any business entity can have a valuation, not just public companies (which you can use market cap as a valuation proxy).
The value of newschoolers is partly the ad revenue, but moreso the value of the community demographics and any data collected on users. Who knows how well they do this (not as well as Facebook obviously), but it's out there in forum posts, comments etc. This could be valuable to advertisers if used properly. Anyone buying would probably do a valuation based on those intangibles, but yeah, I doubt very much.