I have tried and dismissed all comercial and free slideshow features and separate tools. They are either too complex, scale my images to fit the screen, or both.
I want a simple tool with small footprint and no bells and whistles.
So I have put together a little Java hack that fits my needs perfectly - maybe yours too?
Why not try it? It's free!
jSlides Photo Gallery by Lars Ugleberg at pbase.com
It shows all images in the specified directory OR the specified zip-file. Showing pictures that are packages in a single zip-file was important to me because it helps me organize prepared presentations.