"Congratulations Ms Smith, your 2013 taxes have provided 0.01% of the cost of a missile that was just deployed in Afghanistan!"

If we could choose how our taxes were used (a libertarian dream of mine for awhile), we'd have really lumpy funding. Hopefully it'd cause our military to be defunded, but the VA would probably end up taking the brunt of the hit.

Along those lines, I bet the funding of NASA would be even lumpier than it usually is. Don't they have difficulty planning engineering efforts because they're not sure if congress is going to continue funding next year?

Here's a thought: why don't NASA and other gov research institutes have an endowment instead? The government can add in a one-time lump sum and then periodically add the typical budget to the endowment? I imagine this would be pretty hairy though. It could be just another fund to get ransacked by congress on a rainy day, and there'd easily be controversy about how the fund was invested.