It won't stop you from overdrinking, but Rotgutonix will test unmixed drinks (or those mixed with water) for the presence of unadulterated alcohol aka rotgut. The concept has a chemical sensor can detect several alcoholic brands in about 20 seconds.
At present, the device is set to analyze the following brands: Johnny Walker, JB, DYC, Pampero, Brugal and Havana club, although in future version we expect that Rotgutonix will be able to analyze the chemical composition of over 20 well-known brands, mainly rum, whisky, gin, and vodka.
The site also says the device is currently "a prototype still in the marketing phase", but we'll look out for it.
A fun side note: it's designed by the guy who gave the world the Condometric (a condom with a ruler stenciled on it) and the ball and chain student study aid (with built-in unlocking timer). Right then! [Curiosite via Technabob]