Approachability suggestion from a newbie:
Coming here from Reddit, the instinct to upvote is automatic and it stinks to click the arrow and be denied. Also, upvotes only give one karma on Reddit so you think "I have to get 15 upvotes before I can register my opinion? Forget it." I would change the hover text somehow to say say "Requires 15 reputation to upvote (15 rep = about two upvoted answers)".
The other thing I want to get off my chest is that I thought the privilege "talk in chat" sounded like "ability to banter in the comments under each answer," and I was confused trying to find the add comments link. I'd change the privilege name to "talk in live chat," so I'd know whether I was interested in it.
Edit: I shouldn't have mentioned Reddit, I guess. To me Reddit is a shining example of how to get signal out of noise. I am coming from rpg.stackexchange.com, and Reddit is actually superior to Stack Overflow on that particular topic. I would like Stack Overflow to be a mix of Enworld and Reddit, smart answers with upvotes. It works fine except that it's very offputting to newbies.