Holland.com
Details the electricity voltage in operation in the country.
http://www2.holland.com/global/index.html?page=http://www2.
holland.com/global/geninfo/practinfo/electric.html

Kropla
Tells you which voltage, frequency and plug type prevail in Holland.
http://kropla.com/electric2.htm

Tyzo
Look-up Dutch electricity requirements.
http://www.tyzo.com/travel_tools/electricity.html