NabBurg.com

Track My Cash
Want to see where you money has been, where it goes after you spend it? Register your bill at www.trackmycash.com and get updates when your bill gets a hit.
www.trackmycash.com/

Canadian Money Tracker
Site for tracking Canadian paper notes as they "travel" across the country. Also allows for tracking of high/low notes.
www.cdn-money.com/

FindLizzy.co.uk
Track English bank notes around the world as they are handed from person to person.
www.findlizzy.co.uk/

Leapingloot
Ever wonder where your money travels after you spend it? Start tracking your money by opening an account, then enter your bill's and receive e-mail alerts when your bill is entered by someone else.
www.leapingloot.com/

My Euro
Allows users to track Euro notes across Europe by entering the serial number and postal code. Includes statistics and discussion forums.
www.myeuro.info/

Track your cash!
A site to watch specially marked bills travel around the United States
stepon.com/

EurotraQ
Allows tracking of Euro notes and provides a list of the bills which have been tracked the most.
www.eurotraq.com/

Where Have I Been?
Tracks Canadian and American paper currency as it circulates.
www.wherehaveibeen.com/

subnote
Claiming money as a public space and property, subnote tries to recode the singular value attached to the promissory note. As the money is yours and ours.
www.subnote.net/

SEK Tracker
Track Swedish bank notes.
www.sek-tracker.se/