Autodesk Design Review - Design Review lets you view, mark up, print, and track changes to 2D and 3D files.
DXF View - A lightning-fast drawing viewer enables you to view DXF and DWG™ files on Mac
LiteCAD - Create, edit, view, and print 2D CAD drawings using the file formats: dxf, dwg, shp ;Download-Size...
de·caff Viewer - The de·caff Viewer version 3.
ZWCAD Viewer - Cross-Platform .DWG | .DXF | .DWT R12-2013 Viewer
ODA Viewer - ODA Viewer is a web-based software solution that allows you to view the files based on ODA format and you can easily zoom the file for detail visualization.