Miscellaneous web forums:
Slackware Forum at linuxquestions.org
Slackware Forum at Userlocal.com
Slackware Forum at LinuxISO.org
Yahoo Clubs (now merged with groups, I'll have to check what the new urls are. )
http://clubs.yahoo.com/clubs/slackwarelinux
is now
http://groups.yahoo.com/group/slackwarelinux2/
http://clubs.yahoo.com/clubs/slackwarelinuxclub
is now
http://groups.yahoo.com/group/slackwarelinuxclub/
Yahoo Groups (formerly egroups, formerly onelist...)
Spanish Slackware
http://groups.yahoo.com/group/slackware
Brazilian? Slackware discussion group for (Bras) irc channel
http://groups.yahoo.com/group/slackware_brasirc
General Slackware Discussion
http://groups.yahoo.com/group/linux-slackware
Slackware for those trying to "figure it out" beginner and intermediate skill level, I guess
http://groups.yahoo.com/group/SlackwareLinux
Forum for Slackware support give-and-take
http://groups.yahoo.com/group/SlackwareHELP
Oracle on Slackware
http://groups.yahoo.com/group/oracle_on_slack
Linux on the Thinkpad, the list maintainer uses Slackware
http://groups.yahoo.com/group/linux-thinkpad
USENET Newsgroups
alt.os.linux.slackware
alt.linux.slakware Typo'ed newsgroup