Because I was bored and had an hour to kill, I give you…BAC Pal!  A very simple, small program that uses the Widmark Formula to give an estimated blood alcohol concentration level.  Using the list of states, it can then tell you if you are below the legal limit or not.

Yes, there are tons of these things out there.  But how many of them give you the source code in Python?

Download it, play with it, modify it, make it more useful.