I've used/have PhotoToMovie and FotoMagico and they have some excellent features, but SoundSlides is the MacDaddy (WinDoze too) of Slide (photo) to Flash or Video program.
It's has to be the easiest to use program available! Take a folder of photos, load and, if you wish load music or voice over audio and slide (like dominos) the photos where you wish... at point of voice or music, or to go with the flow.
I don't work for the company (who is a one man developer), but consider SoundSlides tag lines "Build for Storytelling." and "Fast and Intuitive" 100% fact.
A first-class program, easy to use and it's output (either flash to web or Quicktime (Mac only add-on feature) is so fine. It's output is very classy! From dummie to master, this program makes a bundle of photos a work of moving to sound art.
Love for the price to be a little lower, but I bought for $69 + QT plug-in and consider THE BEST PHOTO to SLIDESHOW SOFTWARE AVAILABLE. Worth every dollar!
Easy as pie to use and makes an rookie look like Ken Burns.