Here is a good list of active groups, i am sure there are more. of course plenty of binary groups are active to. if one you like isnt that active, why not try to revive it?

alt.culture.usenet:
alt.fan.usenet:
alt.obituaries:
alt.privacy:
alt.tv.simpsons:
ba.broadcast:
comp.ai:
comp.arch:
comp.compilers:
comp.dcom.telecom:
comp.infosystems.gemini:
comp.infosystems.gopher:
comp.lang.c++:
comp.lang.c:
comp.lang.forth:
comp.lang.misc:
comp.lang.python.announce:
comp.lang.python:
comp.lang.raspberry-pi:
comp.lang.tcl:
comp.misc:
comp.mobile.android:
comp.mobile.misc:
comp.os.cpm:
comp.os.linux.announce:
comp.os.linux.misc:
comp.risks:
comp.sys.apple2:
comp.sys.ibm.pc.games.action:
comp.text.tex:
comp.unix.shell:
gnu.emacs.help:
misc.legal.moderated:
misc.taxes.moderated:
news.admin.moderation:
news.announce.important:
news.announce.newgroups:
news.groups.proposals:
news.groups:
news.software.readers:
rec.arts.drwho:
rec.arts.movies.current-films:
rec.arts.sf.tv:
rec.arts.sf.written:
rec.autos.sport.f1:
rec.aviation.soaring:
rec.bicycles.tech:
rec.food.cooking:
rec.games.backgammon:
rec.music.beatles:
rec.music.classical.recordings:
rec.radio.amateur.antenna:
rec.radio.amateur.boatanchors:
rec.radio.amateur.equipment:
rec.radio.amateur.homebrew:
rec.radio.amateur.misc:
rec.radio.amateur.moderated:
rec.radio.amateur.policy:
rec.radio.amateur.space:
rec.radio.info:
rec.radio.shortwave:
rec.sport.rowing:
rec.woodworking:
sci.astro:
sci.electronics.design:
sci.electronics.repair:
sci.logic:
sci.physics.relativity:
sci.physics.research:
talk.origins:
uk.comp.sys.mac:
uk.radio.amateur.moderated:
uk.rec.sheds:
uk.sci.weather:

I logged into my Usenet provider yesterday. I read groups related to my hobbies, so not sure my recommendations would do you much good.