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:
you dont have to pay. you can get an account on google groups or eternal september or one of the other very few remaining text only servers but you get what you pay for. poor interface (google groups) or various account or posting restrictions. no binary groups, etc… for a couple of bucks, you can get better service quality, high message retention, faster speeds etc. it costs significant money to run these servers now with all the bandwidth and hard drives.