I'm reasonably new to SUDOKU, however, I thought it would be fun to build a calculator for working out puzzles. It only works with IE, but has some nice hint /solve features. It supports most of the basic theories that I know like; Naked Pair, Hidden Pair, and others I don't know the names for.
Feel free to test it out, and offer suggestions.
It can be found at http://www.fileexplorer.com/sudoku.html
Enjoy...