[Meetup] lets you manage groups and RSVP to your group events. They have an [api] so that applications like [iMingle] can manage events, comments, and RSVPs. The API does not provide access to [private groups] if you don’t belong to them. Location data may not be available which cripples the app, so you may have to submit location data to [Skyhook Wireless] which provides location data for the iPhone.