It looks like we might be getting a betting exchange here! Check out
http://www.twoflys.com - it is a betting exchange based in the UK but is trialing a service on Australian racing (betting in A$). If you sign up at the moment you get $10000 trial money to play with - they are betting on Cox plate at the moment. Will be interesting to see if they can keep it going - I am sure the TAB's & bookies will be screaming for it to be shut down but since it is based overseas that could be rather difficult.