Oklahoma celebrates its centennial in November -- Happy Birthday, Oklahoma!

Today, Oklahoma is known as one of the most business-friendly states, due in part to low tax rates. Oklahoma's economy is based largely on the energy, aviation, and food processing sectors. From 2000 to 2006, Oklahoma's gross domestic product increased 50 percent. The GDP per capita grew almost 10 percent between 2005 and 2006, one of the highest rates in the nation.

Fortune magazine's 2007 list of the fastest growing companies in the U.S. included six from Oklahoma. At number three on the list was Tulsa-based Arena Resources Inc. (NYSE: ARD), a seven-year old oil and gas firm with a three-year annual growth rate of 165 percent. Back in August, Arena announced strong second quarter 2007 financial and operating results. Arena is also a major holding in the Bruce Fund, which recently made the 2007 Forbes Honor Roll.

Tulsa-based oil and gas driller Helmerich & Payne Inc. (NYSE: HP) had a three-year annual growth rate of 37 percent, which beat the S&P 500. In August, H&P announced strong second quarter 2007 results, as well as two new contracts. The Motley Fool sees expansion in other sectors as good news for drillers such as H&P.

Gasoline inventories dropped below their five-year average and are now 6% below last year's average, according to Joseph Dancy, an adjunct professor at Southern Methodist University, in an essay published in Barron's this weekend.

This means the outlook for investing in energy remains good, Dancy believes, as demand for gasoline will grow 2% with little supply relief in sight. Particularly the lack of new refinery capacity means positive growth prospects for a company like Matrix Service Company (NASDAQ: MTRX) that specializes in repair and maintenance services to the refining, distribution and pipelines sectors.

Dancy wrote the supply and demand balance for energy could mean a sharp escalation of energy prices. Mexico's Cantarell field's output, the second largest in the world as measured by output, declined 17% in March from year-earlier levels, while offset by new production increases at a nearby field, total crude production from Mexico is down 5%. In addition, Venezuela production should get hit at some point as Chavez has taken control of exploring for and producing energy away from the foreign experts. And Nigeria, who sends 1 million barrels per day to the US, is also in a politically tenuous situation.

Add to this, the huge swing producer, Saudi Arabia, announced that is will no longer increase production after 2009, which might indicate the nature of its oil reserves.

In addition to Matrix, Arena Resources Inc (NYSE: ARD), OMNI Energy Services Corporation (NASDAQ: OMNI), Pioneer Drilling Company (AMEX: PDC), Natural Gas Services Group Inc (AMEX: NGS) were mentioned as attractive investment ideas.