Have you ever... looked at the comments on MeFi? Some posts get lengthy, complex discussions, on subjects related to the link at hand; some do not. There is also Ask MeFi, where you can ask questions and get answers from other users (ads shown against this section to visitors without an account used to be a major portion of MeFi’s revenue until Google did some stuff that lowered MeFi’s search ranking). And there’s MetaTalk, which is for talking about the site and has its fair share of “hey let’s hang out and talk” posts.

I mean, yeah, it’s structured mostly around links, and you can certainly use it as a source of Interesting Links. But there’s conversation and community there if you look around a little.