If you've got an image that you'd like vectorized, VectorMagic will do it for you online, free of charge. It's currently tuned to work best with photographs or icons. You answer a couple of simple questions (with sensible defaults) as you upload the image, then sit back and watch it being converted.
"This site is the result of a Stanford University Artificial Intelligence Laboratory research project by James Diebel and Jacob Norda.
We have strived to make the site as easy to use as possible, with a distinct and clear user-interface, while imposing a minimum of fuss. All that is required is a reasonably modern browser, Flash Player and an image you'd like to vectorize."