If you get enough rep you can do some minor moderation see Review but as you say not a lot of value added there as Robert takes care of most of it.
New site proposals that actually have a chance of moving on, tend to be very focused so that for the most part, unless you are existing member of the user group there is not much you can add to the example questions.
Personally I come here out of habit, I read the new discussions, and because I have been reading them for years, I know all the answers to all the questions that get asked all the time, I try to answer some of those, provide context and if still available a link to old related answers.
Not sure there is much else to do. There are a couple of not yet launched sites that I think would have potential of a successful launch, so I keep coming back in hopes of seeing one of them.