Ask HN: HN-style community sites for advertising/marketing and biz dev?

I've found the Hacker News community really helpful in a lot of ways and am often asking aloud "I wonder if there is a site like this for x community to congregate in".<p>At the moment I am specifically looking for something in the advertising industry but I have also been looking for something for up and coming film/tv writers and producers.<p>Any help much appreciated!