Facebook is handy, but essentially unsearchable, it's also 'pull oriented' -- You have to go look. For something that is low traffic this is bad.
Mailing lists are push oriented. You get an email when someone posts to the list. It's easy to search your own mail.
Forums are pull oriented too.
I'd like to find forum software that would allow:
Users to subscribe to a forum -- they get an email for every post/reply to a given subforum.
Forum posts can be also be directed to an FB group. Posting is not allowed directly to the group, but messages can be publicly read.
Ideally the forum allows the creation of blog like entries with images and captions mixed with text.