Display ad optimization startup Rocket Fuel raised $6.6 million in a Series C funding, giving it a $160 million valuation, according to the company. Northgate Capital led the financing. Other investors included Mohr Davidow Ventures, Labrador Capital Fund, Nokia Growth Partners and Wilson Sonsini Goodrich & Rosati. Rocket Fuel processes 1.5 billon display ads ever day for major brands, constantly tweaking them acros thousands of variables to improve their targeting. The company is at a $50 million annualized revenue run-rate, which is up from a $30 million run-rate just four months ago. The company takes a completely data-driven approach to improving display ad performance.