How to create a simulated collage from a photograph?

Here is a very good online tool to create a simulated collage from a single photograph.

Create a unique "collage" from a single photograph. Choose one of two styles: a "joiner" style image without frames or an image created from simulated Polaroids. Every generated image is unique. This toy was inspired by the photo collages of the artist David Hockney. Works with your photos hosted on Flickr or anywhere else. Discussion and comments about this application here.