Kristol, like anybody else, is free to pay voluntary taxes, in excess of what he owes.
Congress should immediately pass a bill as part of the "fiscal cliff" negotiations that provides for IRS forms to "ask" millionaires and billionaires if they want to pay the higher percentages. If so, they can check the appropriate box and pay the extra taxes.
Warren Buffett and the rest of these morons can gladly check the box and write bigger checks, just like they have practically begged to do. And I'm sure they will, lest they expose themselves as shameless, lying hypocrites.
Sure, they really will!
/sarc