I know of a great way to make billions and billions of dollars--and you won't even have to pay taxes on it.

All you have to do is take over the U.S. Treasury Department's Bureau of Engraving and Printing. That's the agency that, quite literally, prints all of our paper money. On average, they print about $67 billion in a year, enough to circle the Earth about 24 times.

Unless you're an alien race with very sophisticated weapons and no sense of decency, it's not really possible to take over the BEP, of course. But it's a fun thought--sitting on top of a $67-billion heap of cash. That's a lot of money.

As a society, we spend an incredible amount of time thinking about money. From the never-ending stock market reports to the stories about how much celebrities make to the lists of who's the richest in the world, we seem to be obsessed with having money. And this is understandable. Money buys us food and pays for our shelter--things we need for survival. It also makes survival more fun, as anyone who has a DVD player and a humongous TV could tell you.

Money is stranger than science fiction
Isaac Asimov, the scientist and science fiction writer, was also a great collector of facts. He gathered some very interesting ones about money. You might think, for example, that coins were the first kind of money humans used. But you'd be wrong. We actually wrote checks first. According to Asimov, ancient Babylonians inscribed checks on clay tablets and used them as their currency.

And that's not all:

• The first United States silver coins came from Martha Washington's silver service.
• No banks existed in the colonies before the American Revolution. You had to borrow from an individual.
• In 1895, J. P. Morgan and the Rothschilds saved the gold reserve of the U.S. Treasury with a $65-million loan--in gold, no less.
• The town of Tenino, Washington, issued wooden money in 1932. Made of Sitka spruce, the wooden coins were worth 25 cents, 50 cents and $1. They didn't make any wooden nickels, though. (I wonder if it's because the phrase, "Don't take any wooden nickels" was, um, coined just a few years earlier, in 1915. The saying was a warning against conniving city slickers to the simple country folk moving to town for jobs. In fact, according to the Encyclopedia of Word and Phrase Origins, no wooden nickels were ever counterfeited. It would have been too expensive.)

• Until the 20th century, dogs' teeth were used as money by Solomon Island natives.
• The Yap islanders in the South Pacific were known to use 18-foot-high stone rings as money. Clearly these are people who, if they wore pants, didn't have pockets.
• The United States once issued a 5-cent bill. Good thing we discontinued the 5-cent bill. Today, it costs a little more than 4 cents to print a bill.
• The life expectancy of a dollar bill is 18 months. But a $100 bill lasts 9 years. (I guess you do get what you pay for. Actually, the reason $100s last longer is that $1 bills get more use.)
• There are about 560 billion dollar bills in circulation. In 1976, there were only $77 billion floating around (and I say "only" with big, sarcastic air quotes). The difference? Foreign demand for U.S. currency has increased. The Federal Reserve actually thinks most U.S. dollars aren't even in the United States--they're overseas.

The future is in your wallet
As interesting as the history of money is, the present is also pretty darned fascinating. If you haven't been surviving on a small island in the South China Sea, you've almost certainly seen some of the redesigned bills in circulation. The $100, $50, $20, $10 and $5 bills all have received face-lifts--the first in 70 years--mainly to foil counterfeiters, who have been using increasingly sophisticated technologies to make their illicit fortunes.

Jim Hagedorn, a spokesman for the Bureau of Engraving and Printing, explains that 13 engravers worked on the redesigns--which they did by hand using a 500-year-old technique that takes years to master. (The apprenticeship, he says, lasts 12-15 years--longer even than medical school.)

Interestingly enough, redesigning all this new money only cost about $1 million. But it cost about $28 million or so to educate the public, both in the United States and overseas, so no one would lose confidence in the dollar, Hagedorn said.

From now on, our printed money will be redesigned every 7 to 10 years, he said. And maybe, just maybe, they'll pick a color other than green.

But don't count on seeing George Washington's face enlarged to match Lincoln and the rest of the dead presidents--at least not this time around. Apparently, the dollar isn't alluring enough to counterfeiters to make it worth their while. Which means that for the next few years we will be stuck with money that doesn't match.

I guess this isn't so bad, though. The old George Washington dollar is the symbol of U.S. currency around the world, Hagedorn says: "That makes it more special."