
1. Arena ResourcesEight-year-old oil and gas producerhas grown by buying properties in New Mexico and Texas.2. T-3 Energy ServicesOilfield equipment maker fills orders from the Middle East to Russia.3. Allis-Chalmers EnergyOil and gas services firm has been on an acquisition binge over the past six years.4. Bucyrus InternationalWisconsin-based manufacturer specializes in equipment for mining coal and copper.5. DXP EnterprisesThis 100-year-old company supplies pumps and more to industries including oil and gas.6. National Oilwell VarcoHouston-based oil and gas services outfit makes products under 115 brand names.