PentoVision
This program uses the technique of backtracking search to explore ways of fitting 'pentominoes' into various shapes. The 12 pentominoes are all the connected shapes that can be made by joining five squares.
Instructions
Use the button labelled Choose to choose a board shape, then click on the Solve button to make the program display all the solutions. You can see the number of solutions found so far in the bottom left of the window.
Click on Quit to exit at any time.