Former military brat Jessie James made her singing debut in 2009 with "Blue Jeans." Its mesh of country and dance pop with just a dash of crunk (part Shania Twain, part Christina Aguilera) was an apt introduction to the singer's playfully radio-ready genre bending. Ultimately, though, for all her music's cowboy prodding and banjo sampling, James is a classic melody-driven pop diva. The Georgian moved swift to a major label, and with songwriting partners like Katy Perry and Nashville guru Kara DioGuardi, she was bound to succeed.