Two nights ago I discoveredrasterbation and I'm hooked.
The Rasterbator is a means by which you upload an image and it is rasterized, made potentially huge (up to 20 meters) and sent back to you as a pdf. I am obsessed and flooded with ideas. My initial test project was a picture of my daughter for my office wall, observe.
I've found some other rasterbaters as well including this HUGE project and thissweet stand alone, given that your chosen platform works.