Discourse is an extremely cool and open source reinvention of forum software that is replete with modern features like real-time AJAX loading of threads (which are not the usual tree-like things but more a flat form with contextual threading as and when needed), lots of collective features including reputation management, tagging, rating and ranking, what's-hot lists and so on. Looks slick, hooks into plenty of other services. I'd like to see something like this on the Landing instead of its simple discussion boards. Not trivial to integrate, but it does have an open and rich API so can be called easily from other systems.