Autodesk, Inc. - AutoCAD and other Autodesk's products

CADdepot - CAD shareware, demos, free utilities and add-ons

GeoCommunity - Free GIS and CAD software

Cadopolis - Large selection of AutoCAD software

3D CAD Browser - Download and upload high-quality 3D CAD models

CBEN.NET - Free CAD blocks

Google SketchUp - 3D modeling program