Got another (free) Windows Phone App in the marketplace:

 The Mobile Breathalyzer

Using revolutionary technology in Windows Phone 7, the Mobile Breathalyzer allows you to determine your blood alcohol content using your phone. Um, yeah, right. Download this joke app and then have your drunk friends try it. Watch them blow into the phone, expecting a result. Good times!

Give it a try! Thanks to @systim for doing the design. Good old designer/developer workflow on this one -- Blend/VS did the trick.