[78-L] What key is that in?

[Malcolm Rockwell]

It just occurred to me... how come there isn't an app or a plug-in for 
Audacity (or any other audio file modifying software) that determines 
the pitch of a file? I'd think doing a quick average of the first few 
seconds could determine the key that the start of the piece is in. Then 
there might be an option that would allow the listener to shift the 
records pitch digitally to raise or lower it so it's in tune to a set 
pitch (like A440).
Another neat trick would be having the ability to show key changes 
within a piece. Maybe like this Part 1 = C; Part 2 = G; Part 3 (1) = C; 
Part 4 = Am; Part 5 (1) = C, and so forth. Note that in my example Parts 
1, 3, and 5 have the same key and melody.
Just a thought.
Malcolm