Who said the U.S. Congress was good for nothing? You and I, probably, but neither of us was giving Carl Levin, John McCain, and the other members of the Senate's Permanent Subcommittee on Investigations their due. In drawing attention to corporate tax avoidance, most recently by hauling before it Apple CEO Tim Cook, the committee is performing an important public service. Nearly everybody agrees the system of corporate taxation is broken. But it is only if the public gets engaged (and enraged) that anything will be done.