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. 

This requires gtkglext.