As seen at http://news.yahoo.com/s/space/200510...estfountainpen
a new fountain pen has been developed that can draw lines as narrow as 40 nanometers across. To put that into perspective, a typical red blood cell is about 7,000 nanometers across. The limit of resolution of a light microscope is about 300 nanometers across. The article suggests some uses like "crafting miniscule protein arrays and complex semiconductors".
One use that immediately comes to my mind is writing licensing agreements on software packages.