potrace is a Peter Selinger's GPLed utility for tracing 
bitmaps - converting them into smooth, scalable images. 

It accepts as input a bitmap B/W images (PBM, PGM, PPM 
and BMP formats), and returns encapsulated PostScript 
(EPS) as the default output. Other output format are 
available: PS, SVG and also PGM.

You can create scalable image formats from scans, such 
as logos, hand taken notes, etc. The resulting smooth 
images can then be rendered at any resolution. 

WWW: http://potrace.sourceforge.net