TeXCAD is a program for the PC which enables the user to draw diagrams
on screen using a mouse or arrow keys, with an on-screen menu of available
picture-elements. Its output is code for the LaTeX
picture environment.
Optionally, it can be set to include lines at all angles using
the emTeX driver-family
\specials.
TeXCAD is part of the emTeX distribution.
A Unix port of the program (xtexcad) has been made.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=texcad