Microfinance has gone far beyond a few small loans to struggling female entrepreneurs. These days it adds up to 10,000 lending institutions, at least 50 million customers and nagging questions about high interest rates. Microfinance may be all about small loans to women running tiny enterprises such as selling fruits and vegetables off a cart. But for the world of finance it's also become a big business. After growing by between 20 percent and 40 percent a year for the last decade, microfinance now involves about 10,000 lenders and at least 50 million borrowers. With loans averaging around $530, billions of dollars are reaching struggling entrepreneurs around the world whose incomes are too low to qualify them for traditional bank loans. With some 3 billion people living on less than $2 a day, the client base of people too poor to qualify for traditional bank loans has plenty of room to grow, say industry participants.