I came across this link via Boing Boing,
Conductive Silver Ink from a Ballpoint Pen
http://www.youtube.com/watch?feature=player_detailpage&v=dfNByi-rrO4
showing the ingredients and how to make it. The ingredients look to be commonly available,
http://www.youtube.com/watch?feature=player_detailpage&v=dfNByi-rrO4#t=95s
Baxter