I just got an idea that i really think would be awsome! What if, in some way you could take a calculation, and create your own expression for it! You would just copy and paste your calculation, select one part of it and click the "use as variable-button" or something, select a name, and it would be added to your list of expressions. This would be a powerful tool to speed up the coding, organize the code, and make it more readable. You could also have a button to inactivate the homemade expressions so that you could read the code as it would look without them.
What do you think?