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, Xfig, PGM, PDF and experimental 
GimpPath.

You can create scalable images 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