IGT is not a company you want to bet against. The world's largest maker of slot machines has always been an innovator: It was the first to link networks of machines electronically so that casinos could entice gamblers with higher jackpots. It has recently been a leader in rolling out machines that pay winners with redeemable paper vouchers instead of coins. Reno (Nev.)-based IGT introduced 94 new types of machines last year. That's a big reason sales grew at an annual average 33.9% rate over the past three years, and earnings at a 35.6% average annual pace.