Dave's Favorites: Make a Photo Collage With Collage Maker
If you like compiling collages, then I've got a tool for you: Collage Maker from Galleria Software. It costs $25, and you can get a 30-day free trial copy.
Collage Maker is a simple program, ideal for kids and digital imaging beginners. Simply select a project size and start loading images; there are presets for common paper sizes ranging from index cards to 11-by-14-inch stock. You can resize and position them to taste, then add text captions and clip art "stamps." The background is customizable with a solid color, color gradient, or a pattern. My favorite feature is the wide assortment of masks that you can apply to photos. These masks blend the pictures into the background in dozens of attractive ways.
When you're done, you can make a high-resolution print of your collage, save it as a photo, or e-mail a small, compressed screen-sized version using your own e-mail application.