Good comunity. In the end, that's all that comes down to, everything on a forum depends on the people that visit it.
I pretty much look for a friendly place to talk about stuff. Profesionalism is good, but it's not my top priority. -JE-
respect, friendships, reliable people, but when i really think about it, a really good community to come to and chill out and talk to people that have the same or similar interests.
Something unique. If you want to start a graphics site, look at sites like iGO or Bratz-Designs, blazeXtreme etc..
Good community. People can make beautiful signatures, but be dickheads. People need to be decent-mannered, and the forum needs a variety of opinions.
Nice members (can't say much for a few people here) who you can trust. Not too big a community too, or else it just gets hard to keep up with everything. A place where you're welcome any time. Yup, that'd be good.
Cause your post right there was helpful huh? What do you want us to write a full essay on what a forum needs? Just make it unique and fun.. we dont even kno what kinda forum...