OpenTable.com has raised $42 million in a fourth round of funding to expand its online restaurant reservation service. Investors included Benchmark Capital, Impact Venture Partners and Integral Capital. New York-based OpenTable provides online reservations to hotel concierges, travel agents and Web visitors. Its system reserves tables at more than 1,100 restaurants in the United States. The company has raised a total of $55 million since its inception in October 1998.