PCB is an interactive printed circuit board editor for the X11 window
system.  PCB includes a rats nest feature, design rule checking, and
can provide industry standard RS-274-X (Gerber), NC drill, and
centroid data (X-Y data) output for use in the board fabrication and
assembly process.  PCB offers high end features such as an autorouter
and trace optimizer which can tremendously reduce layout time.

WWW: http://pcb.gpleda.org/index.html