The Windows Phone app which gone free next as myAppFreeapp of the day is Just Sudoku.
Just Sudoku Details:
Only a Sudoku. But a special one. Since in addition to standard features such as the candidates display, difficulty selection or undo/redo support, a logical solver is integrated in the app. With this logical solver you not only know the next possible number, you also know how to find it out next time. And if you can not solve a sudoku in a newspaper. No problem, because the program also has an integrated scanner. Simply take a picture and read the sudoku automatically.
