From Wikipedia (http://en.wikipedia.org/wiki/Conductive_polymer#History), reference markers removed:

In 1963 Australians Bolto, DE Weiss, and coworkers reported iodine-doped oxidized polypyrrole blacks with resistivities as low as 1 ohm·cm. This Australian group eventually claimed to reach resistivities as low as 0.03 ohm·cm with other conductive organic polymers. This resistivity is roughly equivalent to present-day efforts.

not very conductive. You can used various PeDOT polymers inks but you're best best is usually to go with metallic nanoparticles. Those aren't too great because they limit the number of substrates you can use due to required post-deposition processing (annealing mostly, to make them conductive). We also managed to print nanowires and carbon nanotubes. Those are extremely conductive and require little post-processing. In fact, we did most of our work on paper substrates.