If you're looking to create slideshows or carousel-style views of your photos--much like you can see them in Mac OS X Leopard--you'll want the free Pictomio. It may be the best slideshow and carousel creator you'll find.
Install it, and Pictomio finds all of your photos lightning-fast, and displays them in thumbnails by folder. You can view photos as thumbnails, in a filmstrip view, each photo individually, or the carousel view. For each photo, you get an amazing amount of data, including not just the usual file size, date, and so on, but the shutter speed and aperture used to take the photo, and the kind of data that photo techs will love.
There are a considerable number of tools for organizing and displaying your photos, although very few photo editing tools. Keep in mind that not everyone will be able to run Pictomio; it requires a ShaderModel 2.0 graphics card with at least 128 MB of graphics memory. If you're not sure whether your graphics card meets the requirements, check its documentation.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.