I thought I would just sum up a couple of the more interesting points in the thread:

How does one create a sense of community on a forum? Well, it takes a heck of a lot of work. When starting out, you need to post a lot, joke around, and help people whenever you can. It's time consuming. You have to create an environment that not only is useful for all the members, but a place where members feel that they can contribute and be a part of. Once you have enough members that feel that way, your forum will start to grow and flourish on it's own (to a certain extent). A forum is like a plant - you need to work hard to get it potted, and make the soil perfect for growing, watering it just enough until it actually starts growing. Over time, you can spend less time watching it and let it grow on it's own, just making sure it gets enough water and sunlight every now and then...

admins/mods have to be active, yet not-overbearing, responsive but not intrusive, friendly, yet stern, and jovial without being pushed around.

Sincerity of the members.

Or, the character of the members. If the members are petty, dishonest and insincere, then the forum will be petty, dishonest and insincere. If the members are mature, honest and sincere, then so will the forum be.