A simple e-mail notification when BTC withdrawal address is changed, and lock on withdrawing funds for at least 24 hours after address change, would be nice too (BTCGuild's method)
I'd like to have to have an option of having a code sent to my mobile with a code in it to activate the withdraw. Make the mobile number unchangeable after registration. Only way to change it is when the account has zero balances. Even if the account is hacked, good luck withdrawing.