Scrubbo:
For aussie rules football, NRL (rugby league) and rugby, there are a host of Australian-based books. I understand some, like Centrebet and SportsTAB don't allow members from the US but I'm sure most do.
Some reasonable ones are:
Canbet -
www.canbet.com
DAS -
www.betthe.net
Bill Hurley -
www.sportsbook.com.au
Sportsodds -
www.sportsodds.com
Global Sportsbet -
www.globalsportsbet.com
Sports Interaction -
www.sportsinteraction.com
Olympic also cover most of these codes -
www.thegreek.com
For futbol/football/soccer, you can also try the likes of the British-based outs like 5Dimes, William Hill, Ladbrokes, Blue Square etc.
Car races - Camelot, GCS...
Be worth your while posting the same question in the "Off the Wall" forum - where all the top plays are
, the Motor Racing and Golf Forums too - lots of punters in there with a better working knowledge of the books than me.
I just concentrate on trying to find winners ...LOL
As always, pays to shop around for the best lines - I seem to have more books than the public library
GL