It doesn't happen every day, and it doesn't make much noise when it does. The moment when you get the itch to start a business often happens quietly and without warning--you could be sitting in cafe enjoying a latte or zipping along on the freeway when inspiration strikes. And typically, it's accompanied by nothing more than a smile creeping across your face--because you know you're on to something, and you know you want to keep it to yourself for a while. That's what we hope happens when you read this year's "Million-Dollar Ideas," our 3rd annual look at some of the hottest business ideas around. Pull up a chair, or simply pull over on the side of the road, because you're going to want to take this one in good.