Gerber Viewer is a viewer for Gerber files, also called RS274X. The Gerber Viewer has a batch feature, which is based on Guile Scheme; you can write small Scheme scripts to generate other file formats, do design rule check, etc.
http://sourceforge.net/projects/gerbv/
very small Windows 3.1 application for making wiring diagrams
http://www.geocities.com/SiliconValley/Park/5228/apps.htm
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/
It allows to trace and to print the Bode diagrams, both asymptotic and true, and the analysis (zeros, poles, stabilization to open and closed ring, reaction, regulation, project and verification of control systems). The departure function can be expressed
http://web.tiscali.it/no-redirect-tiscali/hiforce/winbode/indexeng.htm
Viewer that supports all DXF/DWG, HPGL, HPGL/2, JPG, and TIF files, even within ZIP archives, and allows to print them.
http://www.guthcad.com.au/viewer.htm
File viewer, inspector, and translator software for IGES, STEP, VDA-FS, and NC G-code data.
http://www.cadlook.com/
program for drawing publishable-quality electrical circuit schematic diagrams
http://xcircuit.sourceforge.net/
program for drawing publishable-quality electrical circuit schematic diagrams and related figures, and produce circuit netlists through schematic capture.
http://bach.ece.jhu.edu/~tim/programs/xcircuit/xcircuit.html