Wish there was a way for public investors to invest in certain parts of a publicly traded company. If I believe in a certain project at Apple or Google, I want to fund it and get returns on my investment.
The government should work like that with taxes. Instead of just giving 100% to whatever the government decides it wants to fund, 20% could be reserved to go to what people want it to go to. Have some participation in the tax paying. More interesting and better for the world if we apply that to governments rather than companies :)
Under that plan, the best funded parts of the government would be the ones that benefit rich people only.
Then again, considering the intelligence and temperament of the average person, I think in short order we'd have amazing playgrounds and free hot dog stands everywhere, all under the flag of the hammer and sickle.