Add a calculator panel!
A simple calculator panel to basic math. This would be great in ALL Adobe products, in fact.
B Smart commented
Are you aware that all of the shape and transformation tools have calculation built in? For instance, you can click the ellipse tool (or pretty much any tool that gives you an input box) and enter 12/3 in the width box. it will give you a width of 4. Or if you want to repeat a Rotate>Copy put 360/3 in the Angle input box and it will give you 120 degrees. Very useful.