I've had a version of the Cipher Sovler on the web for years. Now I have ported that to the Windows Mobile platform as well.

Simple? Yes. But ever so enjoyable. You can download a trial version here. It  is remarkably similar to the web version, though scaled down to a much smaller screen size. This mean separating the functionality into three separate tabs. One to solve the puzzle:

One to Enter the puzzle:

And one for the statistics:

I need to see about setting it to change size and shape for auto-rotation and adding a time but that's for next week.