A friend of mine came up with this while bored in class; I made it into a little VB .NET app. The goal is to drop the numbers 1-9 onto a 9x9 grid without repeating the same number in any row or column. I'm betting there is an easy pattern, but I just wrote the thing- I'm not good at it. Let me know what you think.
Note: This will install the .NET Compact Framework if you don't have it, which could take awhile.