Ze'ev & mlsoft - flat taxes
I'm afraid I have to disagree. Taxes should be "targeted" in one very important way: the rich should have to pay a higher percentage of income than the poor. The most important secondary accomplishment of taxes should be a REdistribution of wealth downward.
This is not just for sociopolitical ends (else I would not post it here). To keep the economy going, it is critically important that the money be directed toward those who are most likely to spend it immediately, rather than socking it away (the concept of "velocity").
For this reason (and for the sociopolitical ones as well), I am very much in favor of a graduated income tax (more so than it is now), opposed to a flat tax, and even more opposed to sales taxes.
P.S. I do, however, support targeted sales taxes on "sin" items, like alcohol, cigarettes, and gasoline.
P.P.S. I have spent most of my life in the top one percent of earners, so I've had to pay my share of income taxes.