Found this in reddit
http://www.google.com.au/search?q=1.50+aud+per+litre+in+usd+per+gallon
Cool usage of the caclulator feature

You can also use AUD/l in USD/gal

also useful is 256 kb/s in KB/s

You can also try °C / Japanese Yen per km/h in °F / CAD per mph

http://www.google.com.au/search?hl=en&q=7+celsius+degrees+per+yen+per+km%2Fh+in+fahrenheit+degrees+per+CAD+per+mph&btnG=Search&meta=

Who knew? :)