Microsoft Research AutoCollage

Microsoft Research AutoCollage is a tool that spares you the trouble of arranging images in order to create collages. Instead, it automatically does that for you.
The interface of the program is simple, eye-catching and intuitive. You can use only the file browser to add pictures, since the "drag and drop" method is not supported.
Images are automatically displayed in a random order across the interface, but you will probably notice their position change if you resize the window. However, this doesn't interfere with the results.
In the "Options" menu you can specify the size of your collage and set the relative size (top-ranked and second-ranked image, image overlap). Settings can be restored to their default values at any time.
After you set the tool to create a collage, you can either save it in the JPEG format, email it or set it as the background wallpaper. Plus, you can zoom in and out of the picture.
As we have expected, Microsoft Research AutoCollage uses a high amount of system resources, due to its graphical interface. However, it quickly loads images, creates and saves collages. Also, you can check out a brief help file if you don't know how to get started.
The bottom line is that Microsoft Research AutoCollage should probably be used by novices only, since it doesn't offer any kind of advanced settings.