CadStd

A drafting program for Windows, with a free lite version.
http://www.cadstd.com/

VectorEngineer

A multi-purpose 2D CAD system for technical drawings, designs, and isometric visualizations. A free version is available for download.
http://www.vectorengineer.com/

Delta Cad

A 2D CAD software designed to be easy to use.
http://www.deltacad.com/

JustCad

A 2D CAD program for Windows, distributed as shareware.
http://justcad.com/

ProCAD+

A computer aided 2D drawing program for Acorn RISC OS computers.
http://www.dsnell.zynet.co.uk/CADindex.html

Accucadd

A Windows drafting program, the successor to the DOS based RoboCAD.
http://www.accucadd.com/

Malz++Kassner GmbH

CAD 5 drafting software for Windows, with plug-ins to support DXF, DWG, HPGL/2 and SVG file formats.
http://www.malz-kassner.com/

Pressure Vessel Drafting Guide

Detailed instructions on how do design and draft pressure vessels with AutoCAD, with examples.
http://www.geocities.com/ww_chew/pvdrafting/pvd-frame.htm

Dexterpen

A parametric drawing and calculating utility, for creating diagrams of variable geometry objects. Writes DXF files and copies to office applications.
http://www.ransen.com/dexterpen/

General CADD Products, Inc.

About the General CADD Pro 2D Windows CAD program, with user forums and a downloadable manual.
http://www.generalcadd.com/

CAD Schroer GmbH

Manufacturer and vendor of the MEDUSA4 parametric 2D CAD system, and several application specific extensions.
http://www.cad-schroer.com/

Delta Software international

CAD Pro is a drafting and design software with engineering precision and adaptive tools.
http://www.cadprosoftware.com/

ZiPCAD

A drafting program for Palm OS handheld computers, with DXF file export.
http://www.zipcad.com/

TigerCad

Budget 2D CAD software for mechanical, architectural and diagrams.
http://www.tigercad.com/

QCad

A 2D CAD system for Linux, Unix Systems, Mac OS X and Windows, released as Open Source for unix based systems.
http://www.ribbonsoft.com/qcad.html

A9Tech

Offers the general-purpose 2D CAD program A9CAD supporing industry standar DWG and DXF drawing formats, and the DWG/DXF translator A9Converter, both free.
http://www.a9tech.com/

AllyCAD

A 2D CAD package for the architectural, civil, and mechanical industries.
http://www.allycad.com/

AndyCAD

A low cost general purpose 2D CAD program.
http://www.andycad.com/