Bill Hobbs has an interesting op-ed on reforming Tennessee's tax system in today's Memphis Commercial Appeal; it's worth a read. Most of the objection to the Sundquist income tax was that it would potentially open the floodgates for profligate spending by the legislature; Bill's plan would help allay those fears.
His plan's probably worth implementing in Mississippi, too, which already suffers from a byzantine income tax (with bizarre effects at the low end) and relatively high sales tax.