LG is about to release a cellphone to the US market with a built-in breathalyzer:

The LP4100 also allows users to set up the phone so on certain nights and after a certain time they do not call certain people in their phone book. Think ex-boyfriend or ex-girlfriend.

If you have a blood alcohol level over .08, the phone will not let you dial that person. So it not only promotes sobriety, but chastity — and probably your dignity, as well.

Link via Schneier on Security.