Picasa is an easy to use, and free, photo website. It is mostly used for people to store their images online. But you can also upload a group of your photos and the site will arrange them into a collage layout which you can easily print out. You can even edit the photos turning them into black and white images, sepia, or use a range of their photo effects.
All of this was the basis for the DIY photo lamp shades done by Marie highlighted on Under The Sycamore. Marie used Picasa to create a collage of her photos, turn the images into black and white and print them out onto one sheet of Vellum. She then trimmed the printed out piece and hot glued it onto a lamp shade. She also created another version of the lamp using one of the photos effects on Picasa which turned each photo into a different color. You can find the tutorial over at this post.