Chats or forums whose main focus is submitting of original writing for online viewing and discussion belong in the Online_Writing category.
To maximize visibility, first look for the most specific category for the community. For example, if the main focus of your community forums is Science Fiction, your best bet would be to submit to Science Fiction and Fantasy/Message Boards and Communities/. Likewise if your main focus is discussion of a specific author or book - like ''Stephen King'' or ''Harry Potter'' - check to see if these categories have an area for forum communities.