Any similarities between a large, well-known investment firm and an adult Web site is purely coincidental, or so says Rob Muller. He’s the man from Holland who has Goldman Sachs heavily breathing down his neck over his goldmansex.com. Goldman has filed a complaint with the National Arbitration Forum, which adjudicates domain-name fights, arguing that there was a likelihood of confusion between the firm and the site, which carried material that Goldman, understandably, finds objectionable. Muller claims he only recently heard of the firm, while friends nicknamed him “Goldman,” he says, because he was so lucky. Time will tell whether his Web site name – and his luck – will hold.