Forum Moderators: open
Sometimes referred to as majordomo or listservers after the software that runs them. They exist for every imaginable subject. Basically, you submit your email address, and email starts arriving from all over the world on that subject. Some lists are moderated, some only allow members to post, and some are wide open. Sort of the email cousin of forums.
There's a lot of good give and take between participants, but there can also be annoying drivel. Any of this could inspire a good article.
Common questions asked (solutions are usually quickly supplied) just beg for an article with a clever title.
And if there's a magazine for a topic, you can bet there are some associations. A [keyphrase site:.org] search can turn up troves of information and contacts. And don't forget the .gov and .edu tlds for some specific types of info.