AEC VIZ(site info)
A 3D DXF/DWG viewer for the AEC market, offering cross-sections, shadow calculation, and real-time manipulation of large models.
http://www.aecviz.com/
iTwinView(site info)
An online service for viewing CAD files in your web browser through a Java applet, as well as software for file viewing and conversion.
http://www.cad2dtp.com/