You're asking about an admin forum specifically, right? Like another TAZ or a general web dev forum?
Either way, something that could make it different... create a less professional environment for a change.
You've obviously seen the recent activity on TAZ that is basically talking about TAZ itself, forums in general, and other meta topics. I remember reading a post that said it best: Most of us having been doing this for years and/or are burnt out on "how do you moderate your members" type threads. Ironically, I think the example they used was "what should my next forum be about" threads like this one, lol.
So yeah, most of us are still here to talk about industry news/drama, to ask for casual advice from one experienced admin to another, and to just shoot the **** with people (usernames) that we've known for years.
That being said, I think it would be interesting if it was an admin/web dev forum for us to let loose a little bit. It could be as simple as having literally only two sections: on-topic and off-topic.
It could have a satirical vibe to it. Valuable on-topic discussion mixed with loose moderation and friendly banter (and XF vs. IPS memes?).
An old webmaster forum called WickedFire used to be just like this and I always found it to be an interesting option for people like us. It's still online running the legendary vB3:
https://www.wickedfire.com
I was recently messing with a test board based on this idea (only for fun though). I think I have a list of possible names, one being Tired Admin Zone, lol.
Edit: Here's the thread where I was talking about this:
https://xenforo.com/community/threa...l-witty-names-for-a-blog-about-forums.200281/