There's no telling what a $10 investment in U2 in 1985 would be worth today, but a start-up Web site called Sellaband is offering music fans the chance to put their money behind artists they think can climb the charts. The Amsterdam-based company allows fans -- or what Sellaband calls "believers" -- to invest in unsigned acts in $10 increments. Once an act reaches $50,000, it is given access to a recording studio and professional production, songwriting and marketing expertise.