I always wondered what would happen if we ended taxation completely, and instead have the government create new industries that would generate profits, which would then be used to pay for services. For example if the government nurtured a new kind of technology. The U.S. government has been in business before, its spending has spurred the creation of new inventions.
We could create a national university and make a deal with students: we'll pay for your degree in chemistry, if you work in our lab and whatever you create becomes property of the United States, allowing the government the exclusive right to sell it.
That is a bit far in my book, but I am very sympathetic to a system where the government mines/extracts the resources
(fossil fuels, precious metals, other things like that) and sells it with a focus on domestic sales/uses. The idea being that if we're going to dig up and utilize all these finite resources from our own land, we - the people - might as well benefit from it, as opposed to a small number of wealthy executives/investors. Perhaps some sort of system with mining on private lands could be done, but with the govt taking a substantial cut of the profits that come from those resources.
Resources may never be an issue again if we can efficiently mine asteroids/other planets/moons, but as it is now, we only have a finite amount of these things, and I'd rather the benefits of what we have be shared than hoarded among a limited number of people.