Vectorizer.io - Fast and easy way to vectorize an image online
Splashroad Separation Studio - Quick and Easy Color/Shape Separation
potrace - Open source program that transforms bitmaps into vector graphics.
Rasterbator - Wall art from any image
Autotracer.org - Free online image vectorizer
Posterizer - The rasterbator allows you to create posters larger than a standard page, using the tiled printing method. It will rasterize any image and output files that can be printed at home and reassemble to the original image.