Sunrise Coding Screensaver is a nice application that allows you to display a slideshow with your images as a screensaver. The images shown can be in a local folder or can be obtained from your Picasa account. If you choose the latter, you just have to enter your Picasa account details and select exactly the folders you wish to show. The images will be shown with a black background and they will appear in the center of the screen.
The application will also allow you to select the duration of every image on the screen, define the scroll effect used (which can be random or you can specify the direction) and the sort mode (random, one by one in order or sorted by name). Moreover, if you want, you can also show the name of the files shown. Sadly, you won't be able to add music to your slideshow or select another type of transition effect, which is really a shame.
In short, if you are looking for a simple and free screensaver to display your photos in a slideshow, Sunrise Coding Screensaver may be a good choice.
