Electric is a sophisticated electrical CAD system that can handle
many forms of circuit design, including:

   Custom IC layout (ASICs) 
   Schematic drawing 
   Hardware description language specifications 
   Electro-mechanical hybrid layout 

(snip, this is an edited version of Electric's homepage)

Electric handles these file formats: 

   CIF I/O 
   GDS I/O 
   VHDL I/O 
   DXF I/O 
   PostScript, HPGL, and QuickDraw output 

For real functionality, one should consider installing
support simulation software such as cad/spice.

WWW: http://www.gnu.org/software/electric/electric.html