I think we can all agree that there should be clarification between ServerFault, Webmasters, StackOverflow. See, Webmasters appears to be the median, since many webmasters need to both manage servers and make sure code is correct. As for promoting more interest, maybe do a cleanup of all the very bad questions, and encourage people to update old-questions' answers with relevant, modern information (HTML5, etc.). There are TOO MANY questions about SEO that are TOO similar.
We can also either diversify or centralize the user-base, by trying to reduce the number of people who make one question and then never register their account or come visit again. This can be done in a very simple manner, of "require one answer" to post a question.
That could be taken both ways, because it might increase the number of low-quality answers we have. A simple rule could be imposed, "all answers by level-one members have to be moderator-approved." But again, this can be discussed.
Furthermore, many of the questions on StackOverflow can be migrated here, perhaps for the double-win. SO tends to have so many questions that it's nearly impossible to read them all without clicking "refresh" every ten seconds. So many questions go unanswered for the longest of time there, unless someone upvotes it quickly.