Vector Magic is online tool developed ad Stanford University that converts bitmaps to vector images. This is a great tool, very easy to use and with great results. Just upload your image, and it will be converted online and available for you to download in vector format. Most of the bitmap images are supported. Finished vector image can be downloaded in EPS or SVG format.
RubyPDF Blog English,Mic VectorMagic-a free online tool that converts bitmaps to vector images(ESP or SVG)