By now we've all read the anonymous Congresscritter's memo calling for some sort of gratuitous (but feel-good) slap at the worst offenders of the bailout crisis--a moment in the public stocks. Congressperson X suggests mandatory credit counseling, but I don't think that's humbling enough. A regulatory lifetime ban on working in the financial services industry (or related fields, or lobbying) would be better, but that's still just enforced early retirement.
I think a better idea would be some sort of deal whereby, in exchange for criminal immunity and civil indemnity, the various Bad People would agree to do community service. A hell of a lot of community service. 10,000 hours (five years' worth, if they're industrious about it) sounds about right for the top echelon.