TIPS or I-bonds would seem to be the prototypical example: they guarantee a certain real rate of return (about 2% when I looked a couple years ago, though I heard it's gone negative with the credit crunch), so if you've got $10M or so you're guaranteed your $200k. Only thing you have to worry about is a government default, but if they do that, you have bigger problems to worry about than what happened to your money.