This is where I got the idea from: Exposure Calculator
The Calculator/Comparison allows you to do 2 things:
1. Enter in ISO, Shutter Speed, f-Stop (maybe even exposure comp, but that is probably overkill) manually.
2. Have it pull from the meta data of open files/photos.
In each side (Exposure A, Exposure B) there are input boxes to enter in the information manually, along with a drop-down menu of the currently open files to choose from to auto fill from the meta data.
I know it's already available else where, but to have it in the app would be great. And maybe I am the only one that would find this useful. Thanks!