For any range of topics, lighthearted to serious, hobbies and games to helping and engaging with community matters. Regarding reach, I mean what ways may be used alongside word of mouth, as I honestly don’t hear people talk about groups they’re in (besides sports/bands) all that much.
I think posters/flyers are one of the most powerful ways to reach people in a local area, you’ve got to be in the local area to see them, right?
Another way to spread the word can be via the internet, Facebook is god awful, but a lot of communities will have something akin to a noticeboard that is another effective way to get the word out.