Online travel giant Priceline.com ( PCLN) is another name that's enjoying stellar relative strength in 2013. Shares of the firm have climbed more than 16% since the first trading day in January, and that trajectory doesn't look like it's set to slow down in March. Priceline is one of the world's biggest online travel sites, offering bookings for hotels, airlines, rental cars and vacation packages such as cruises and tours. The firm's ongoing acquisition deal with Kayak (KYAK) stands to boost the eyes on PCLN's network and give the company a more content-driven site. Kayak joins other properties like Booking.com and Agoda in filling out Priceline's non-core web properties. That strategy of reaching beyond the firm's eponymous website is critical for delivering growth among disparate market segments this year. Here at home, there aren't many big economic moats in travel anymore -- the U.S. travel market is largely commoditized at this point thanks to "lowest price" guarantees with hotels, a phenomenon that effectively means that it doesn't matter where you buy your next trip. But there is a lot more flexibility abroad, particularly in emerging markets in Asia and Latin America. And that's where Priceline has been focusing its attention. A solid balance sheet with a hefty net cash position (even after the Kayak acquisition) round out the picture for this firm.