Where's George

A website, www.wheresgeorge.com, devoted to tracking the location and condition of American dollar bills of all commonly-used denominations as they travel throughout the country.

In order to use Where's George, a person enters the denomination, serial number, and series (date) of a bill, his local zip code, as well as optional notes on its condition and where it was obtained, into spaces on the webpage. The person then marks the bill with Where's George's URL, either by writing it along the border in pen or using a rubber stamp, and spends it. It is up to the next person or persons to have the bill to repeat the process.

Where's George came under government scrutiny shortly after its inception for selling rubber stamps with which to mark the currency. It is against the law to deface currency in a manner that would make it impossible to spend or reissue, though whether a simple rubber stamping would constitute such defacement is questionable. Where's George has since stopped selling rubber stamps, however.

A similar tracking site for Canadian currency is called "Where's Willy". Also similar is BookCrossing, which uses the same principles for tracking literature.

Georging Tips

• Whether you use a rubber stamp or just write the URL on the bill, don't obscure the bill to the point that it cannot be used. Writing on bills is legal, making them unusable is not. (Some vending machines won't take bills if you make the mark too large - this does not mean the bill is unusable. Just give it to a real person.)
• Spend in locations that are likely to have good turnaround. Convenience stores, tollbooths, and fast food restaurants are good places; vending machines are not.
• Only enter bills that you have in front of you. If you want to mark a bill but you're not in front of the computer, don't enter it later - this could result in a false "reverse" hit. Mark the bill and send it out - perhaps someone else will start Georging someday. (If you are in front of a computer and have no way to mark a bill, go ahead and enter it - but if it leaves your hands unmarked, don't expect it to hit very soon!)
• Give cashiers larger bills for smaller purchases. They won't like this very much, but you will get more bills in change, which can then be marked.
• Be patient.

My source for this was personal experience but additional information may be found at wheresgeorge.com (official site) and wheresgeorge.net (fan site).