I’d be interested in this too. You can find a limited amount of good information on the most active groups at the bottom of this page: http://news.eternal-september.org/postingstats.php. I’ll be adding some of those myself!

I currently read the following active groups:

• alt.comp.software.seamonkey
• alt.folklore.computers
• comp.infosystems.gemini
• comp.infosystems.gopher
• comp.misc
• comp.unix.shell
• linux.debian.user
• misc.news.internet.discuss
• netscape.public.mozilla.seamonkey
  `

Of those, I’d say comp.misc is the most interesting (kind of like the Hacker News/Lobste.rs/Slashdot), though it seems to have slowed down lately.

I also follow and post to some relatively inactive groups in the hope that they’ll revive, especially alt.sports.hockey.nhl.vanc-canucks.

Maybe other people could post the newsgroups they follow? Or someone could suggest a means of automating discovery? I might even write to eternal-september and ask them to publish a longer list of active newsgroups. Update: I wrote and asked if they could post a list of the “Top 100” most active groups.

Lastly, you can also find some good leads on active newsgroups on Reddit, if that suits you: