"R-U-Buzzed," a free application released Dec. 2 from the Colorado Department of Transportation, allows you to quickly determine your blood alcohol level. Simply spin the wheel to your weight, how many drinks you've had and the amount of time you've been drinking and the app will tell you if you're safe to drive.Additionally, the app allows the user to contact a cab, although this feature only searches for cabs within Colorado. The app will guide users in other states to links for cabs in their areas.
There is also this:
One app that claims to provide more precision in determining users' blood alcohol level is "Last Call" from Avvo.com, a website that helps people find and select lawyers.
Last Call requires the user to input more detailed information on the size and type of drinks consumed, and tracks the amount of time drinking automatically.
This blogger will be staying home on New Year's Eve and does NOT advocate drinking and driving! iPhone apps are sometimes useful and sometimes just toys. Be smart!