The suggestion above is for a vector format .dwf file, which will require a plug-in to be installed by anyone who wants to view the drawing. This may complicate things a bit in both ends. Other than that, it is a great technology.
If you want to use a raster format file instead, I think it is best to start with a hpgl-2 file generated by a plot. Because the hpgl file is generated by a plot, you will have full control of line color, resolution and line weights in the finished output. To create hpgl files from Intellicad, install a printer driver capable of producing hpgl-2 files. I use the HP Designjet 750C driver available from
www.hp.com. Remember to set up the driver so that it prints to a file, not a port. Change the default extension .prn to .plt in the output file.
After you have successfully created the hpgl (plt) file, it must be converted to raster format. I have not yet been able to find a freeware utility to do this (others might be able to help). A 30-day trial of View Companion Professional should do the job for you. It is available from here:
http://www.softwarecompanions.com/dnfiles.html
You will now have an uncompreesed .tif format file with the resolution you desire, which should be converted to .gif format for web posting.