On the flip side, they were only "alive" because people -- like me, like you -- posted to them. So they're dead, but like Lazarus they can be resurrected by commanding them to be alive, through the simple mechanic of using them, and encouraging others to come participate.
Since then, comp.misc has been a rather nice place.
EDIT: Corrected the newsgroup name. Note to self: don't drink and type.
I don't think you'd find that on HN at least.
I feel like since just anyone can sign up for Usenet these days instead of just the technologically motivated, communities like them have been altered significantly.
Still, there are still interesting threads, and with judicious application of PLONK (something you can't do on modern web forums like HN, by the way), you can make the worst idiots out of your sight.
I'm always up for more newgroups to hold my interest. Another poster mentioned comp.misc is active, so I'll probably start checking that one out as well.