Rapper and music producer Sean "Diddy" Combs is hip-hop's original mega-mogul, having branched out into movie and TV producing, acting, restaurant ownership and -- most notably -- fashion, since hitting it big in music in the 1990s. Combs launched Sean John in 1998, and the line quickly morphed from a basic urban label into an international brand and men's department staple around the world. His success as a fashion tycoon paved the way for Jennifer Lopez, Gwen Stefani and other musicians-turned-designers. Revenue for Sean John exceeds $100 million annually. Not too shabby for a side business.
Shawn "Jay-Z" Carter launched urban clothing brand Rocawear in 1995, with Damon Dash -- his partner in the influential hip-hop label Roc-a-Fella Records. The brand, which initially capitalized on rap's saggy, baggy look, has matured into a more trend-based lifestyle label with urban flair, offering plus-size clothing, accessory, fragrance and kids lines, along with its signature street wear. Jay-Z sold the Rocawear rights to Iconix Brand Group in 2007 for $204 million, but Beyonce's other half -- who personally prefers a classic tux to jeans -- retained his stake in the company and remains active on the marketing and product development fronts. Annual sales in 2008 topped $700 million.