With civ5 money finally has value! No longer is money only a negotiation tool till 'Democracy'. One can use money to purchase buildings and units, bribe city states and buy tiles! It now pays of to save money and there are several choices to make when you want to spend your money.
Formerly known as "CyberShy"
Carpe Diem tamen Memento Mori
Money had value from the first moment I preordered Civ 5.
You can simply concentrate on building libraries to give you a boost to the technology, "Commerce" and then building Markets on all of your major cities. Then you can simply hoard enough money to buy units at command. So you can enjoy bountiful income in peacetime where you don't have any units, and then when war comes, you buy yourself an army and destroy the opposition. Then delete all your units, and enjoy more profit
Except this strategy is almost useless in any difficuilty above Emporer.