SketchUp - 3D for Everyone
BricsCAD - A powerful CAD platform, with features familiar to you from native .dwg applications.
Autodesk Revit - Autodesk Revit is building information modeling software for architects, structural engineers, MEP engineers, designers, and contractors.
iCADMac - User friendly 2D/3D CAD software for MAC OS X, which reads and writes DWG format drawing files.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
AutoCAD LT - AutoCAD LT is a drafting tool to create 2D drawings.