Thermal calculators
http://www.novelconceptsinc.com/calculators.htm

Hundreds of CPU heatsink tests in real world conditions
http://www.madshrimps.be/?action=getarticle&articID=389

Thermal conductivity
http://en.wikipedia.org/wiki/Thermal_conductivity

Properties of metal – Thermal
http://www.engineersedge.com/properties_of_metals.htm

Thermal Conductivity of Metals
http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

Heat conduction calculator
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatcond.html#c1

Thermal conductivity unit conversion calculator
http://www.gordonengland.co.uk/conversion/thermcon.htm