I made a program to automatically save screenshots one takes with the printscreen key. I have found it to be pretty useful for a couple of games I play. , if you're interested.
I've also been toying with making a sort of text to speech application, using prerecorded sounds which are played together. h+ell+oh. k+uh+n+s+t+r+uh+k+t. That sort of thing. I'm using the Direct-X runtime, however, as I am calling functions with a delay. It's not exactly a game, at least, and looks like an application. :b
It's more fun to use than the command-line C version I made years ago, and more advanced, too.
Someone could make a simple text editor, for sure.
I could see it being used for a paint program of some kind, too, if you don't mind using the Direct-X runtime.