As a developer, we have the iPhone Simulator and can run the iPhone programs right on a Mac for testing. Couldn't you package the same code so any Mac (and maybe even Windows) user could buy and run any iPhone app directly on their computer too? As part of iTunes or something, launching them in separate windows so you could have a couple running at once.
There are many that would be pointless (ooh, a flashlight!)...but might be kinda cool for others. And would give anybody with a Mac a taste of what they could be running on an iPhone or iPod touch.