[Zope] Killer features for a user group site?

Hey My question is: What are the best features for a user group website? I'm working an a site for the local Zope user group. I want it to keep it simple and easy to use. Furthermore I want to actively involve the members for content-contribution. Therefore I'm concentrating my efforts on the following elements (in order of importance): Mailing lists, meeting announcements, a few small introductory articles and news items. Are these the best features? Are there any better ones? Sincerely, Tue Wennerberg