I have implemented a javascript version of Donald Knuth Dancing Links algothrym. It can solve any Sudoku program and tell whether there are none, one or multiple solutions.
You can see it at http://sudoku.pjoneil.net/Sudoku_Solver.html
The javascript source code can be downloaded if you want.
The main difference between my free sudoku program and this dancing link solver is that the sudoku program uses human based logic to solve the puzzle and can single step thru the solution.
Any comments would be appreciated.
Pat