You upload your photos (or import from Facebook or Picasa), arrange them in the order you want, add music, and you're done. The site has demos and easy to follow guides, along with a great help page. There is also a gallery of public slideshows you can view for inspiration. You can make the show play as a story, with zooming on the pictures, or as a spiral effect. Check out the demo!
Teachers could use PhotoPeach to create slideshows for their classes as presentations, as review materials, or as an online discussion focus. Students could view the slideshow and comment on it. Students could use it to create projects - story lines, research projects, and more.
You can share your slideshow via email, IM, Twitter or Facebook. You can also embed them in your blog or website.
It's free, powerful, and easy to use and is a nice alternative to other presentation methods.
(There is a premium edition that offers some extended features.)