Description, software, and circuit diagrams for a homebuilt video digitiser
http://www.techmind.org/vd/vidmk2.html
The machine will do a reasonable job machining soft materials like plastic and soft woods, and it does quite a good job of plotting PCBs. The idea was to use a Dremel tool for the cutting head and use the machine to engrave aluminum front panels.
http://www.storm.ca/~rheslip/cnc.htm
An autonomous robotic project designed to explore its surroundings with a 360 degrees field of vision. Site includes photographs, sub-system descriptions and parts lists.
http://members.shaw.ca/selwyn.rd/
http://www.smarthome.com/howto04.html
http://www.web-ee.com/Schematics/Hornet/hornet.htm
http://www.e-insite.net/ednmag/archives/1994/060994/12df4.htm
http://www.edn.com/article/CA149115.html
University of Illinois at Urbana - Champaign research project consisting of self-propelled and self-controlled hovercraft floating on a airhockey-type table.
http://legend.me.uiuc.edu/hotdec/
workings of lead-acid battery.
http://www.batterycouncil.org/works.html
http://www.wvic.com/how-gen-works.htm