Smilebox helps you make cool slideshows, postcards, and greetings out of your photos.  They have a very informative demo, and they also show you some great examples of what you can make with their service.  You have to click on “take a tour” in order to view the demo and click on the samples on the homepage to see what you can make.  If you want to check out my demo, go here.

Smilebox Demo