KiCAD is a cross platform (Debian, Gentoo, OS X, Ubuntu, Windows...) and open source electronics design automation suite.
It permits the creation of electronic schematic diagrams and PCB artwork.
It comes with an ensemble of the following stand-alone software tools:
- KiCad
Project manager - Eeschema
Schematic editor (both schematic and component) - CvPcb
Footprint selector - Pcbnew
Circuit board board editor - GerbView
Gerber viewer - Bitmap2Component
Convert bitmap images to components or footprints - PCB Calculator
Calculator for components, track width, electrical spacing, color codes, and more… - Pl Editor
Page layout editor
More details: kicad-pcb.org