Regarding karma, this is one place where I think HN's implementation gets it right (or at least more right than others). You can see your own karma, and the votes of things that you've submitted (I'm talking about comments not stories here), but you have to go look to see anyone else's, and you can't see the karma they've gotten from their comments (except as a relative number versus your own comment at the same level within a thread).

There are surely still karma whores (I'll admit to liking seeing the little number next to my name go up) but it's not quite as in-your-face as somewhere like Reddit.