Description of /UIImages .png's?

As someone who is very new to theming the biggest problem I've had is determining which .png relates to a certain graphic on my iPhone4. I just recently came across the /UIImages extracted .png's which is fantastic for the really easy items like Black_DataTypeUMTS.png (3G symbol) etc. but only somewhat helps for things like TopShine.png (Area between status bar and search bar in safari).

So for all the expert themers out there (and I know there are a lot, I've seen so many beautiful custom themes here) how do you know what all the UIImages .png's are? Is there a list somewhere? I've started to make one in excel with file names, a description, and image sizes but I imagine someone has already beat me to the punch.

 

Yeah I've been doing that with UIImages folder I downloaded which is fine for things like the battery charging etc. But for the status bar and then the search bar in safari, bottom bar in safari etc. they all look the same as a .png but do quite different things. Those are the .pngs that I would love a description for if it exists.