Even better... allow for the two way link to include a mathematical expression for each direction
Even better... allow for the two way link to include a mathematical expression for each direction. One equation for the forward link, one for the reverse. By combining many links, a complex mathematical tree could be created where a user could type in a value anywhere in the tree of cells (from the trunk out to the leaves) and see how the tree evolves.
3 comments

Kenneth Barber commented
You're suggesting that cells can contain a value and a formula rather than just 1 of them. Interesting.
Your suggestion is basically saying that we should be allowed to define a mathematical relationship and easily change which variable is unknown. It's somewhat like logic programming.

Nick commented
I like this idea  it would be extremely powerful.

Robert Keefover commented
This is an additional improvement to my first suggestion:
Add a method to create twodirectional cell links. Typing in any one of the cells updates the other linked cell. Currently the only way I know this can be done is through VB scripts in "thisworkbook".