Keri Hilson started out as a songwriter and backing singer, but the Atlanta performer's star turn was a propulsively airy vocal on Timbaland's 2007 club banger “The Way I Are”. That breakthrough established her as an R&B singer with dance-floor vibes, a role she's since perfected on solo tracks like the futuristic hip-hop stomp of “Return the Favor” (another Timbaland collab) and the electro-R&B whoosh of “Lose Control / Let Me Down”, which features Nelly. Uptempo club isn't Hilson's only forte—she's also a fine power diva, as evidenced by her cathartic flutter on the ballad “Energy”.