mmm ummm well depends on what you count message boards and such on.
but:
this.
http://slashdot.org
http://kuro5hin.org
http://tfproject.org (good site, big board there)
http://eslcafe.com (esl stuff)
http://forumosa.com (taiwan stuff)
http://fark.com
http://metafilter.org
now if you wanna include blogs as well....