Well, you need to make sure that whatever your topic is, it is a strong, defined subject. "Chat site" won't get you shit. You need to narrow it down and whittle away excess garbage. Furthermore, you want to make sure that you word that subject in such a way that is inviting. RMRK's name is good because we are a resource. We are not RPG Maker Games Kit. This would imply we're a service, or a team, and that this is a place to discuss our work. By making ourselves a resource we are inviting the individual user inside to create and discuss- to show off. People love to talk about themselves.
So, that in mind, what do you think your site would be about? We can't tell you, you have to decide. If you don't stand behind the topic fully, you can't give it your full and undivided effort.
Summary: Do not generalize, pick a strong and accessible topic, and embrace your potential user.
That said, this is all opinion.