I use GIMP for image-processing software, but I never bothered to learn to draw with it. My CAD has a schematic-capture portion as probably all do, but there are things about
all schematic-capture programs that I don't like, so I still do my schematics by hand, doing the biggest ones on a large drawing board. I draw quite small to get the most complex circuits on an 18"x24" velum (and may mark in the title box something like, "Page 1 of 2"), not going any larger because I don't have the room. Kinko's can make photocopies up to at least 48" wide, with the length being even greater, on bond paper, unlike the old blueprint process.
A neighbor gave me a used scanner I use frequently to digitize hand-drawn diagrams, but it won't even go up to 11"x17", let alone 18"x24". After a page is scanned, I use GIMP to get rid of the stray marks, make the background totally white (so data is not wasted showing the grain of the paper), etc.. An example on my website is the basic whole-computer schematic at
http://wilsonminesco.com/6502primer/pot ... ml#BAS_CPU which I drew on an 11x17" paper and then reduced on a photocopier before scanning. I got very proficient at using OrCAD for schematics at my last place of work, but will not go back to it.
Jeff seems to be the .gif expert around here, generating the nice repeating motion-picture diagrams.