kicad

KiCad is an EDA software suite for the creation of professional schematics and printed circuit boards up to 16 layers. KiCad runs on Windows, Linux and Apple OS X and is released under the open-source GNU GPL v2 free of charge.

http://www.kicad-pcb.org/display/KICAD/KiCad+EDA+Software+Suite

Software tools:

eeschema, schematic editor.
pcbnew, printed circuit board editor.
gerbview, GERBER file viewer.
cvpcb, footprint selector for components association.