American Association of Petroleum Geologists (AAPG):
http://www.aapg.org/

Independent Petroleum Association of America (IPAA):
http://www.ipaa.org/

INO.com (NYMEX Crude Oil Futures Prices):
http://quotes.ino.com/exchanges/?r=NYMEX_CL

INO.com (NYMEX Natural Gas Futures Prices):
http://quotes.ino.com/exchanges/?r=NYMEX_NG

New York Mercantile Exchange (NYMEX):
http://www.nymex.com