Sometimes it’s hard to understand how a particular design is going to work from a user experience standpoint, especially on a mobile device. With the Prototypes application you can quickly turn design comps (or even wireframes and sketches) into a tappable/clickable prototype on the iPhone, iPod touch or Mac. Basically, you’ll be turning the images into image maps that will load the appropriate image with touched or clicked. Hosting is included, so once you’ve created your prototype, you can easily share it with anyone. That last bit is a really excellent feature, which makes testing prototypes that much easier. Prototypes is available for $39.99 in the app store.