I agree about no referral codes (except perhaps in the signature if not intentionally used as the main message like using a large and bold font or huge image).

After all, most new bitcoin options (pools, exchanges, vendors, etc.) are largely discovered by posts here.  Referral codes could be banned outright if people abuse it in signatures, but I suspect most if not all will be responsible.  Besides, I only know of one referral code scenario right now anyway and they don't even need to offer it thanks to their competition.