Thoughts and a suggestion concerning off-topic items.
kgermino: I agree that its very hard to determine whether the problem is the content of the sites (Politics ect.) or the visitors to them.  As much as I'm against complicating HN with sister sites and categories I think that if nothing else it would be an interesting experiment.  If it were developed I would certainly check it out and I think that if it was set up similarly to HN it might work.  I feel that the best thing to do is set a sister forum up as a beta limited to HN users with a certain karma level (Although I recognize that this would probably exclude me) and see what happens.  The only way to know what would happen is to try it.  If it doesn't work and the site degenerates into a reddit than most users from HN will stop visiting it and it falls apart; if it works than it can it be opened to a wider array of users.  I say try it.