TGC (Paul) has an app out for practicing for the driver's tests in the UK. I can't remember the name and can't find the reference for it.
Someone also did a Basic editor/compiler (a bit redundant, but interesting).
AGK has all the basic bits for a non-game application. It comes down to designing and executing it.
Most of the people working with AppGameKit are doing games. But there is nothing to stop anyone from doing something else (I have a couple of non-game ideas that might get done after my WIP is done.)
But I don't think anyone has posted code for a non-game.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master