RUNNER-UP: Opodo.com
Opodo was also competitive, offering a fare of $121 on the Brussels–Madrid route. The site is sometimes called the "Orbitz of Europe," since it was founded by that continent's major airlines.

BOOKING FLIGHTS IN ASIA
WINNER: Zuji.com

WHEN TO USE IT: To save a bundle on flights throughout Asia.

WHY WE LIKE IT: Zuji, owned by Travelocity, is a pan-Asian portal with links to online agencies based in seven countries; the prices found on those home country sites often yield much bigger savings than you'd find anywhere else. For example, for a 14-day advance booking on a round-trip flight from Sydney to Auckland, Zuji's Australia-based site offered a nonstop fare on Air New Zealand for $370, which was $284 less than Kayak for the lowest rates on the same carrier. And Zuji's Hong Kong–based site posted a $195 round-trip Hong Kong–Tokyo fare on Shanghai Airlines, while the lowest fare on Kayak was $564 on Northwest Airlines. To be fair, the Northwest flight was nonstop, while the Shanghai Airlines itinerary included a connection, but for a savings of more than $300, we wouldn't mind a short stop (Kayak didn't list the Shanghai flight).

CAVEAT: Fares are offered in local currencies, so you'll need to convert. Stick to the English-language portals— Australia, Hong Kong, and Singapore (Zuji has sites for several other countries, but they will pose translation problems for anyone who's not fluent in at least one Asian language).

TIP: The Zuji Travel Secrets page provides user blogs with opinions on destinations, accommodations, dining, and other areas of interest.

RUNNER-UP: Vayama.com
Vayama performed much better on Asian itineraries than European ones, even edging out Kayak by $28 on the Sydney–Auckland route. The site hosted one million visitors within four months of its launch last June, and promotes itself as being "100 percent focused on international travel," covering airlines, hotels, and rental car companies in 190 countries. We especially like that it allows access to many foreign low-cost carriers, either through direct links or specialty partner sites.