ePic is a US $3.99 OS X app for displaying photos in attractive ways. It has some realistic physics, and unlike many similar apps, you can interact with the onscreen slideshow.
To start, you point the app at an iPhoto or Aperture library, or to online sources like Picasa, Flickr, 500px or any local folder of images.
Then you select a style and begin the show. ePic can run in a window, or full screen. It can also be activated as a screensaver after a set time.
Some of the effects are old hat, like Ken Burns dissolves and slow zooms, but there are some interesting screens where framed photos float in and bounce slightly on a virtual desk. You can interact with slides, using gestures to zoom, rotate and change images. Of course, you can passively sit there and watch the images change and move on their own.
Most of the effects are already in your Apple screensaver preferences, and iPhoto can do some nice slide shows too, plus integrate music if you like. Although ePic is simple to use, one control is called 'playing a round' which is not explained. The app has no help, but does provide a link to the developer site. I went there and still couldn't find an explanation of that option, although a note from the developer told me it lets a slideshow with a finite number of images repeat.
ePic is a nice simple screensaver with a few unique effects. It's worth a look if this app offers an effect you crave, or if you just want a simple way to generate quick slide shows.