I am struggling with framing my question, and that's really my problem. I am not quite sure how to identify the thing that I am searching for. Expert's Exchange has a content restriction system that works very elegantly: nice visuals, SEO friendly, great workfow, etc. I've seen similar things in other websites like Quroa or Just Answers.
I am looking for an equivalent that's "out of the box" ready to be implemented. What I need, is a Joomla based one, but this thread is more about just collecting info on existing tools for other CMSs. I am more interested in learning about features/options rather than just finding a product - today.
I've gone through the extensions directory, so far have found nothing close. Obviously, ACL is present, so the issue of blocking content is not what I am after. I am looking for the streamlined and elegant way in which it is done here.
Any advice will be much appreciated.