Ask HN: Programming for a touch screen interface?

HN,

In the past, I've been entirely a software programmer and haven't come close to the fence between software and hardware. However, I would now like to experiment with some ideas that would utilize a touch interface.

I shy away from utilizing an iPhone or a laptop's touchpad, though. Are there feasible ways to acquire a touch screen with USB connection - or is there a (relatively) cheap way to create a resistive touchscreen with little prior knowledge?