A 3D cad modeling software whose development has been suspended by the creator since he doesn’t work on CAD anymore. Worth a shot considering that it’s a small download.
http://www.le-boite.com
< 1 Megabyte

A quick and easy mapping package. Coordinates can be entered using the mouse, typed in, or imported from external files. Scanned topographic maps, air photos and other bitmap images can also be incorporated. The [...]

A simple cad software that’s continually improved over the years. The freeware version does not have some crucial features like trim, offset, fillet and chamfer.
http://www.cadstd.com/
< 1 Megabyte

Leonid Nemirovsky’s “Better than Nothing” routines are considerably better than most. He also has some tips and tutorials that you might find interesting. He has consistently updated them over the years.
http://home.pacifier.com/~nemi/

A set of very useful routines by Asbjørn Værnes includes a block manager, a layer manager and a detailed door insertion tool among others.
« not updated of late »
http://autolisp.3utilities.com/

This is a collection of almost everything for the Cad user - SHX fonts, hatches, LISP routines and Blocks. There’s even an old collection of drivers in case you have some old equipment lying around.
« Not updated since 1999 »
http://www.cadresource.com/library/

Free Cad Blocks are available at The Cad Block Exchange Network. You can preview most of the blocks before downloading.
« Recommended »
http://cben.net/

CAD Files for Woodworkers gives you details and drawings for woodworking projects.
http://members.telocity.com/lorenh/

This is a block resource for designers who make use of AutoCAD and 3D Studio Max. It is regularly updated.
http://www.iobjects.co.uk/

This is an easy to use unit conversion program that will convert the most popular units of distance, temperature, volume, time, speed, mass, power, density, pressure, energy and many [...]