I don't know much about elsewhere, but here in the U.K we have a progressive tax system with 0%, 20%, 40% and 50%. I believe that a progressive tax system is much fairer than a flat rate one as I believe that those with more income have a duty to pay proportionately more tax.
Where I think our tax system fails is that it generally (with the exception of inheritance and capital gains) taxes income rather than wealth. I read in the New Statesman not too long ago that 1% of the U.K population owns roughly 70% of the land in the country. If a 'land tax' was introduced and it had a threshold high enough to not include most farmers, believe that it could produce a much fairer tax system.
Being somewhat a social democrat, I believe that tax should be raised for targeted areas (higher top rate, reduce ISA limit, etc) to finance a more enabling state. I do believe however that some indirect taxes should be reduced as they are regressive.
