One of the things I least enjoy about paying taxes is that, for all practical purposes, I have no say in how the money is spent.
This wouldn't be so bad, except that I would probably not spend my taxes the way Congress does. Leaving aside billions in pork, farm subsidies, the national endowment for the arts and the occupation of Iraq are not things I would choose to fund. (You may have different priorities and that's fine. That is kind of the point of this fantasy.)
Note that I'm not suggesting that my tax burden should be reduced; there are needs and lots of them to be met with our tax dollars.
While I recognize it will never happen, I wonder what our spending priorities would be like under a taxpayer driven system:
Once your tax bill was computed you would log onto a website where you could allocate a portion of your income taxes to specific programs. First, a portion would be taken to pay interest on the national debt. Then, you could allocate the remainder of your tax payment to any other program. You would see the allocations of other people and could adjust your own until the end of a cutoff period. If you chose not to allocate a portion of your taxes, that portion would go to paying down the national debt. (Congress would still have the power to make interim allocations in an emergency.)
Taxes other than individual income taxes, such as corporate income taxes, could be allocated proportionately or, in the interests of equality, in proportion to the equally weighted allocations of all individuals. (This second option would mitigate one of the obvious criticisms of this proposal: that it gives more power to elites than to the average tax-payer. This is a valid criticism. I hate to disillusion you but it applies to our current system with at least equal force.)
While I suspect that spending patterns would differ, overall spending would reflect the will of the American people more closely than it does now. As a side effect it might well boost civic engagement significantly.
I know there are legions of issues with the above, but still a nice tax day fantasy, to be thought about and then put away until next year.