Free National Geographic Screensaver shows lovely images of animals from all over the world. You will see images of lions, tigers, monkeys, rhinos, frogs, and lizards, to name but a few. The images are shown randomly and they are shown with a different transition effect. Sadly, you can look at them for a couple of seconds and you cannot change this option. There is also an ugly caption at the top with the developer's name and website, which cannot be removed.
From the Settings menu, you will be able to select whether you wish to show transition effects, but you cannot customize which effects you want to see. You can also select the duration of the transition effect, and show a digital clock in any screen corner of your choice. A good thing is that the slideshow can be controlled using predefined keys specified in the Settings menu. The images the screensaver includes can be exported to be used for other purposes.
In short, if you like animals and you are looking for a screensaver which displays lots of images of great quality, Free National Geographic Screensaver may be a good choice.