Taking a page from the online social-networking phenomenon, three Harvard Business School students have launched the UpDown.com to give portfolio managers and traders — real and wannabe — a way to have ideas peer-reviewed. “People originally thought Wikipedia would be crap. But ordinary people have created great content, ” says one founder, German-born Michael Reich. Site Participants manage virtual $1 million portfolios and earn cash if they consistently outperform the Standard & Poor’s 500. Reich and Co. hope to eventually commercialize the site by using participants’ ideas to start a hedge fund or mutual fund or by selling the data to an existing hedge fund.