There has been some previous discussion of the association bonus, c.f. 

+ http://meta.mathoverflow.net/questions/435/the-association-bonus
+ http://meta.mathoverflow.net/questions/60/is-there-an-association-bonus-for-this-site

> Can we please get rid of the association bonus?

I've just had to waste some time writing moderation messages to someone with no MathOverflow questions or answers; I wouldn't have had to if we didn't give the association bonus. I have seen no evidence that the association bonus has benefited MathOverflow.