Autodesk Design Review - Design Review lets you view, mark up, print, and track changes to 2D and 3D files.
ZWCAD Viewer - Cross-Platform .DWG | .DXF | .DWT R12-2013 Viewer
LiteCAD - Create, edit, view, and print 2D CAD drawings using the file formats: dxf, dwg, shp ;Download-Size...
Creo View Express - Creo View Express is a simple CAD tool to review a 3D design for a quick evaluation.
progeCAD - progeCAD is DWG/DXF-native CAD software, built for professional drafting.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.