Startup(s): Facebook

Did you know Bono owns a private equity firm called Elevation Partners? Neither did we. Turns out Elevation Partners manages around $2 billion in assets and manages investments in companies like Yelp and Palm Inc. (Hey, they can't all be winners.) But in 2009, Elevation invested $90 million into Facebook for a 1.5% stake in the growing social network. When Facebook went public was valued at $100 billion, Elevation's, and therefor Bono's, stake in the company was valued at a cool $1.5 billion, making Bono one of the richest, if not the richest, rock star of all time.