http://wiki.answers.com/Q/What_is_the_most_electrically_conductive_material

What is the most electrically conductive material?

Answer:

Superconductors are materials that offer no electrical resistance whatsoever but the highest temperature any known superconductor can be while retaining its conductive properties is -181 degrees Celsius, making them an extremely impractical and expensive material for most purposes.

As far as I know the most conductive material at room temperature is pure silver, which is slightly more conductive then pure copper and 50% more conductive then pure gold.

Copper and gold are both used commonly for conduction however because copper is much cheaper then silver and nearly as conductive, and gold is more resistant to corrosion then either silver or copper despite its reduced capacity for electrical conduction.