Open Source CAD Software

Another one on the 'work in progress' is FreeCAD http://www.freecadweb.org/ essentially Solidworks without the licence, but very much actively evolving. However it would be nice if http://www.freecadweb.org/wiki/index.php?title=Cam_Module started to see some progress. The drawing modules work well, but the full 3D take a little getting used to ... just like Solidworks!

LibreCAD is an alternative 2D drawing package and benefits from GCoC input to add features http://librecad.org/cms/home.html

QCAD predates LibreCAD and had a both commercial and community versions, but LibreCAD can be considered the next generation of free QCAD. Neither actually have a CAM module yet which is where the LibreCAD fork of QCAD started life

Eagle is difficult to beat and the free versions can be more than adaquate. I'm still running an old copy of EasyPC myself and the latest update is £59 but the fact that they have extended the deadline yet again shows that free versions of PCB software are fine. But I'd probably recommend http://kicad-pcb.org/ for anybody just starting with PCBs and circuit diagrams. None of the restrictions of Eagle, and a growing library of components and the 3D viewer is impressive.