When I've taken classes online, I've gotten a sense of community from a few different things:

1. Clear, specific days/times when the instructor will be online and available to provide synchronous help or facilitate discussion. In some cases these sessions have themes and in some cases they do not; both ways have benefits and drawbacks.The key is that all students know that an opportunity to connect exists. I've found these to be particularly helpful when an assignment is looming, but I think it's also a good idea to provide more general sessions.

2. Video introductions before the class starts and/or just after the semester begins. I've only ever seen the instructor set up a video introduction; students usually post something in a discussion thread. But having students upload videos right at the beginning of a semester will help everyone see each other as individual people not avatars. (video shouldn't be mandatory though)

3. Fun things. In "meatspace" a class environment sometimes diverges into randomness or side trips that are unexpected by the students (and sometimes the instructor!). Having something novel like this in cyberspace can add that element of fun that can spark interesting learning opportunities and help everyone enjoy each other's company.