Warren Buffett's article about taxation and tax rates has spawned some very good blog posts on the subject of taxation and who pays for what.
Here is a good post on the subject by John Goodman. In it he proposes a progressive consumption tax. There are things that we could do short of that. For example I wonder why we have a cap on how much a person can put in an IRA. Why not tax income when it comes out of the IRA to be consumed, rather than when it is earned. Investment helps us all in the longer term so why tax it?
Also it would seem to me simpler and better to tax a husbands and wive's income separately and let them divide the exemptions optimally. This would eliminate the marriage penalty making conservatives happy and would encourage more women to work in the taxed part of the economy making Democrats happy.
Of course I would also eliminate most deductions to simplify.