Potrace is a utility for tracing a bitmap, which means, transforming a bitmap into a smooth, scalable image. The input is a bitmap (PBM, PGM, PPM, or BMP format), and the default output is an encapsulated PostScript file (EPS). A typical use is to create EPS files from scanned data, such as company or university logos, handwritten notes, etc. The resulting image is notjaggylike a bitmap, but smooth. It can then be rendered at any resolution.
Check out the examples for a demonstration of what it can do. With this I could finally get that t-shirt printed with the Punisher logo!