I think mefi is a little bit different too, as I understand it, the main revenue come from ads on the Ask Metafilter pages. It certainly isn't growing very much, but I don't believe it's actually declining.

I've been away from slashdot for quite a while (I have a 4 digits username there), I checked the beta site, and while it looks a bit bland to me, I don't get why it is such a big deal for the active users. Would love to have pointers that describe exactly what happens/why it's happening now.