It's not really surprising that an Aussie developer has created an iPhone App that lets you monitor your alcohol consumption in real time to give you a fair idea of your blood alcohol percentage during a night on the booze. The app works by setting up a profile based on your gender, height and weight and your target blood alcohol content. Then as you have a drink, you add it to the app, along with the time you drank it. As time goes by and your speech starts to slur, the app will give you an approximate BAC reading.
The biggest problem I see with this type of app is that as time goes on and more and more drinks are consumed, how likely are you to remember to update the app? I've had plenty of nights where I've lost count of the number of drinks I've had. You should also remember that the BAC figure you're given is an approximation, and won't help you if it says your under the limit but get busted for drink driving anyway.
Still, for $2.50 it's a fairly comprehensive way of monitoring your boozing ways. And it's all Aussie, all the time, which is reason enough to pick it up.