Tried and True Business Ideas Turn a classic business idea into your next big moneymaker.

There's a simple reason some businesses tend to always do well. People love food and convenience, so burger joints and pizza delivery will always be in style. There's always a market for back-to-school products and Christmas tree decorations, too, so retailers have a tried-and-true formula for those seasons. And when it comes to college guys, it's a good bet that they'll always love a good swimsuit calendar.

That's exactly what entrepreneurs Ben Leis and David Freedman were banking on. The two childhood friends came up with a concierge business for sports professionals while Leis was at the University of Miami and Freedman was at Arizona State University in Tempe, but during the planning phase, they decided the business would be too much to handle. Looking for a simpler idea, the pair holed up in Freedman's house, brainstormed and landed on the idea of a swimsuit calendar featuring the girls next door: Arizona State University students. Eight weeks later, they'd formed StudentBody Marketing and already had the Tempe12 calendar out. "It was extremely fast," says Leis. "Eight months later, we had our second calendar out."