Foil, Graphics & More's Scanning Slideshow for Mac OS X is a tool for photographers and display designers who need to show a slideshow or projection of images, and to update the show with newly shot images on the fly. It's up to version 1.0.1, which is a maintenance upgrade — although there are still some stability issues to be addressed.
There are few other slideshow options that will update the folder of images as it runs. Even Mac OS X's built-in system screen saver won't continually update the folder contents. Nor will iPhoto.
With Scanning Slideshow, you can set the length of image display, and choose from several image transition types as well as transition directions. Image file types can be filtered, so only images of a certain kind (ie JPG, TIFF) are displayed but others are ignored (for example, when a photographer shoots RAW JPG, only the JPG version would be displayed on screen).
The slideshow can be shown in a floating window or in full screen mode. The full screen display can be any display the Mac will display, including iPads using Desktop expanding software such as Air Display.
When it works it works well. However, after purchasing it from the Mac App Store, I had trouble launching the Scanning Slideshow at first. Plus, it has crashed a couple of times on me, and I'm not sure why.
Scanning Slideshow is available only at the Mac App Store for US$9.99 in the Graphics & Design category. It requires Mac OS X 10.7 or later.