Credit: Jamie McCarthy/

Celebrities-turned-designers like Jennifer Lopez and Madonna may want to take notes from Jessica Simpson. After all, her eponymous line of products have made close to a whopping $1 billion in 2010.

The Jessica Simpson brand includes more than 20 categories of fashion and accessories including shoes, jeans, swimwear, watches, and fragrance.

"She is the girl next door and has great product that surrounds her," Vince Camuto, founder and CEO of Camuto Group, which is Simpson's licensee, told WWD. "People like her. People look at her as a style icon."

Simpson's dedicated fan base helped retail sales of her brand rocket to $750 million in 2010.

"Her celebrity has created a brand that is more sustainable than many others," said Jack Gross, CEO of Jeanswear for The Jones Group, which licenses Simpson's denim.

What's the 30-year-old's next move? Next fall, she will debut her sportswear line full of jackets, knits and dresses all under $150.