On Fri, 8 Feb 2008 00:30:14 -0600, Dallas
wrote in
:

you really
have no way of knowing the alcohol content of that top shelf margarita that
the friendly bartender made for you at the restaurant.

That is true, but you can be aware of your BAC:

http://www.breathalyzer.net/index2.html
http://www.intox.com/products/handheld.asp
http://www.craigmedical.com/AlcoScreen.htm