This spreadsheet was the winner of the first round of the Resolver One Spreadsheet Challenge, in January 2009.
It numerically solves Poisson partial differential equations (PDEs), and is set up to help you easily perform an electrostatic analysis of a microchip - something that would normally require software costing $20,000!
It could easily be adapted to do other analyses best performed with PDEs - for example, you could use it to work out seepage underneath a dam, or to solve thermodynamic problems, like heat conduction through a body.
To use it, download the ZIP file (using the button to the right), unpack it, and then load the file "finite_difference.rsl" into Resolver One. A simple model is loaded; click on the "Solve model" to perform the analysis. You can then graph the solution using the "Visualization" buttons below.
Two other models are provided as demonstrations in the "models" directory, which you can load up with the "Load Model" button. You can also create your own by populating the grid with appropriate numbers and clicking on the "Save Model" button.