Some ideas

- Allow people to "invest" in other individuals and the investors return would come from the tax revenues paid by the recipient of the investment. For example: Person X, pays 5000 which is applied to Person Y's college expenses. In return some % of persons Y's federal (or state) taxes go to person X for a set number of years. So Person Y does not pay back person X directly, the federal (or state) govt does. But the government would come out ahead if the total taxes paid by person Y are increased enough by the investment to more than offset the payback to person X. Everybody wins. The only serious downside to this idea is a privacy issue. If person X is paid directly from person Y's taxes, person X has a good idea of what person Y is making. This may seem in a way like indentured servitude, but it is really not. Person X has no control of person Y at all, just a stake in his taxes. Person Y is free to do whatever he chooses, free to take any job he wants. Of course person X has a stake in person Y's success so he is an "interested party" so to speak. That makes the situation interesting. You would probably want to make a prohibition against investing in close family members. Perhaps a website could be set up to match up investors and those looking for capitol in this way.

- Pneumatic tubes to deliver the mail in dense urban areas. This was actually done in New York and several other cities around the turn of the 20th century but was abandoned due to motorcar (later auto) delivery of the mail. Now cities are choked full of to much traffic and energy is a huge issue. Key question(s): 1) how much energy does such a system use vs delivery by truck and 2) can such a system handle high volumes. In Chicago there was a whole series of underground tunnels that delivered various kinds of freight until the depression. Part of the rationale for both systems was to alleviate congestion. Why did these systems fall into disuse and why were they replaced. The easy answer is the automobile but I think the real answer is slightly more subtle. Usage of both systems fell sharply during the depression and then after the depression a deliberate decision was made to favor the auto industry which received all sorts of tax breaks and incentives and this may have sealed the fate of competitor systems. Even deeper, the U.S. and to some extent the rest of the developed world has moved in the direction of mass market capitalism as the vehicle for prosperity and progress. Coherent systems - perhaps "centrally planned" in some way fell out of favor. Post WW II progress stemmed from mass production of autos, mass production of TV's, mass production of washing machines and so forth. Europe joined that party. But is the mass production regime the best regime for all sectors of society in the 21'st century? In the realm of transport doesn't it lead to less efficient use of energy and space?