Building That Mousetrap: In early 2000, when Julia Rhodes was an eighth-grade teacher, her high school son asked her to get his basketball coach a gift -- a whiteboard and markers for diagramming plays. "But he told me to get markers with erasers," she said, "because the coach was always using his hand or his shirt." Rhodes couldn't find markers with erasers. She was amazed. She was frustrated. And she was inspired.

Four years later, Rhodes isn't a teacher anymore.

Instead, she is a walking, talking, strutting testimony to the entrepreneurial golden rule of finding a need and filling it. She is the inventor, patent holder, outsourcer, marketer and distributor of KleenSlate -- a whiteboard eraser that comes in two sizes to fit various brands of whiteboard markers.