I am interested in choosing a good structure for an online message board-type application. I will use SO as an example, as I think it's an example that we are all familiar with, but my question is more general; it is about how to achieve the right balance between organization and flexibility in online message boards.
The questions page is a load of random stuff. It moves quickly (some might say, too quickly) and contains a huge number of questions that I'm not interested in.
The idea, I imagine, is that we can use tags to find questions that we're interested in. However, I'm not sure that this works: you can't use tags negatively. I'm not interested in PHP or perl or web development. I want to exclude such posts. But with the tags, I can't.
Although discrete subforums are in a sense less flexible, as they generally force you to pick a category even if a question might fit into two (if SO had, say, areas for "Web Development", "Games development", "Computer Science", "Systems Programming", "Databases", etc. then sure, some people might want to post about developing of web-based games, for example) is it worth sacrificing some of that flexibility in order to make it easier to find the content that you are interested in, and hide the content that you are not interested in?
Is there any way with a pure tagging system to achieve the greater ease of use that subforums provide?