PhotoSketch is an online tool created by five students from Tsinghua University in China and the National University of Singapore. It creates storyboards from sketches by finding & stitching background images & item layers.

We present a system that composes a realistic picture from a simple freehand sketch annotated with text labels. The composed picture is generated by seamlessly stitching several photographs in agreement
with the sketch and text labels; these are found by searching the Internet. Although online image search generates many inappropriate results, our system is able to automatically select suitable photographs to generate a high quality composition, using a filtering scheme to exclude undesirable images. We also provide a novel image blending algorithm to allow seamless image composition. Each blending result is given a numeric score, allowing us to find an optimal combination of discovered images. Experimental results
show the method is very successful; we also evaluate our system using the results from two user studies.

Via Creative Review

http://www.creativereview.co.uk/cr-blog/2009/october/photosketch