Rapper Kanye West is a rumored investor in music start-up Turntable.fm, which raised $7 million this summer. The company lets users discover music by placing them in a virtual DJ room in which they can rate songs up or down. Popular rooms include: "Indie While You Work," "I Love the 80s," and "DJ Wooooo's House/Dance/Electro." As of September, the site had more than 600,000 users and streamed 1 million songs a day. One of the most buzzed about start-ups of the year, Turntable also gave a board seat to high-profile venture capitalist Fred Wilson of Union Square Ventures as part of the investment.